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DRUPAL HTML HTML5 JavaScript jQuery LAMP MySQL PHP

PHP ARCHITECT QUESTIONS AND ANSWERS

What’s the difference between  <SPAN> and  <div> tags?
Span is for inline elements. Div is for block elements.
<div>tags are block elements that allow you to position elements contained within block.
tags used for inline styling of text.
<div> tags create line breaks, <span> tags doesn’t.
div elements are placed in a row, in other words automatic break is inserted. Whereas in case of span elements all are coming one after the other without any breaks.
Note: Can change inline element into block level element through CSS and vise-versa.
div{display:inline}
span{display:block}
Explain Data encryption in PHP ?
The PHP crypt() function can be used to encrypt data.
MD5 is a one way HASH
base64_encode is for encoding data.
Echo, print, printf – what is the difference between these?
Print and echo both output what is passed to them. Print acts like a function, so you can use it in complex statements. Printf is used to format the output
how variables are passed to functions by reference and by value?
A variable is passed by value unless the variable is passed with an &, such as functionName(&$variableName)
How can I execute a PHP script using command line?
PHP script using command line can be executed using SAPI
(Server Application programming Interface). Using SAPI
Command Line Interface the PHP code can be passed to execute
directly
Example:
Php –r ‘print_r(get_defined_constanrs());’
php filename
From a shell/cmd prompt, php –v will display whether the SAPI is CLI or CGI
explain YAHOO’s 20 points for web performance optimization ?
1. Flush the buffer early [server]
2. Use GET for AJAX requests [server]
3. Post-load components [content]
4. Preload components [content]
5. Reduce the number of DOM elements [content]
6. Split components across domains [content]
7. Minimize the number of iframes [content]
8. No 404s [content]
9. Reduce cookie size [cookie]
10. Use cookie-free domains for components [cookie]
11. Minimize DOM access [javascript]
12. Develop smart event handlers [javascript]
13. Choose <link> over @import [css]
14. Avoid filters [css]
15. Optimize images [images]
16. Optimize CSS sprites [images]
17. Don’t scale images in HTML [images]
18. Make favicon.ico small and cacheable [images]
19. Keep components under 25K [mobile]
20. Pack components into a multipart document [mobile]
FMI : http://developer.yahoo.com/performance/rules.html
What are all the new changes in PHP6 ?
Here is the list :

  1. FILE_BINARY and FILE_TEXT constants available for use with filesystem functions.
  2. register_globals will be gone.
  3. magic_quotes will also disappear.
  4. $HTTP_*_VARS has been removed, in favour for $_GET, $_POST, etc.
  5. ereg() no longer available in core PHP6.
  6. Initiating objects with the reference operator (& new Object()) will generate E_STRICT error.
  7. E_STRICT error messages are included in E_ALL errors.
  8. {} for string offsets no longer available.
  9. [] un-deprecated for accessing characters in a string.
  10. ASP-style tags can no longer be used.
  11. Better Unicode Support.
  12. var will be an alias of public, and raises E_STRICT warning.
  13. Support for 64 bit integers.
  14. With ternary operator, the “true” expression is no longer required – this can be done: $a = $s ?: ‘b’; (Not clear yet exactly how this will work).
  15. zend.ze1_compatibility_mode removed.
  16. safe_mode is being removed.
  17. Freetype1 and GD1 support removed.
  18. dl() is only enabled when a SAPI layers registers it explicitly.
  19. Support for dynamic break levels removed.
  20. XMLReader and XMLWriter will be in the core distribution.
  21. mime_magic removed from the core.
  22. Fileinfo moved to the core.
  23. ext/soap on by default.
  24. foreach supports multi-dimensional arrays: foreach($a as $b => list($c, $d))
  25. microtime() will return as float by default.
  26. opcode cache included in core distribution, but turned off by default.
  27. flags parameter available for file_get_contents().
  28. before_needle parameter added to strstr() – allows strstr() to return part of haystack before occurence of the needle.
  29. namespace, import, and goto become reserved words.

FMI : http://blog.tuvinh.com/one-minute-with-php6/

Categories
CSS DRUPAL JavaScript LAMP MySQL PHP

Drupal 8 Interview Questions and Answers

How do I add external CSS OR JS libraries in Drupal 8 ? 

You need to add external library (CSS, JS) into your_theme.libraries.yml and attach the library either in twig or in your controller


myLibrary:
js:
https://xyz.com/bootstrap/4.1.11/js/bootstrap.min.js: { type: external, minified: true }
css:
component:
https://xyz.com/bootstrap/4.1.11/css/bootstrap.min.css: { type: external, minified: true }

{{ attach_library ('mythemename/mylibrary') }}

What is TWIG ? 
Drupal uses a new theme engine called Twig. Its a flexible, fast, and secure PHP based theme engine.its templates are written in a syntax that’s less complex than a PHP template and easier to create interactive and more functional Drupal templates using Twig.

What is Clean URLs ? 
user-friendly URLs, or search engine-friendly URLs, are Uniform Resource Locators (URLs) intended to improve the usability and accessibility of a website is called Clean URLs.
In Drupal 8, ‘Clean URLs’ are enabled by default and can’t be disabled. Check your site’s URLs which should not contain ?q= within the URL. It has certain dependencies on Webserver modules to work properly.

Which are all the Symfony components used by Drupal 8 ?
Symfony Components used by Drupal 8 project :
ClassLoader
Console
CssSelector
Debug
DependencyInjection
EventDispatcher
HttpFoundation
HttpKernel
PHPUnit Bridge
Polyfill Iconv
Process
Routing
Serializer
Translation
Validator
Yaml

how to improve DRUPAL performance for anonymous and authenticated users ?
Anonymous Traffic
Lighter user, basic configuration and performance tuning should handle more use cases.

Authenticated Traffic
Heavier user, can lead to more complex configurations to handle load and performance.
Caching for Drupal Websites

so here are five of the most important caching solutions for a Drupal website:

Drupal’s built-in caching
Boost module
Memcached
Varnish
Views caching

Categories
LAMP MySQL PHP

12 Essential PHP Interview Questions

 Our Toptal Engineering Blog has published a great post called “12 Essential PHP Interview Questions,” and I think it would be of interest to all of you.
See the preview of article given below :
Consider the following code:
$str1 = ‘yabadabadoo’;
$str2 = ‘yaba’;
if (strpos($str1,$str2)) {
echo “\”” . $str1 . “\” contains \”” . $str2 . “\””;
} else {
echo “\”” . $str1 . “\” does not contain \”” . $str2 . “\””;
}
The output will be:
“yabadabadoo” does not contain “yaba”
Why? How can this code be fixed to work correctly?
To see more goto : www.toptal.com/php/interview-questions

Categories
DRUPAL LAMP MySQL PHP

Mindtree – DRUPAL interview questions

1) how to improve DRUPAL performance for anonymous and authenticated users ?
Anonymous Traffic
Lighter user, basic configuration and performance tuning should handle more use cases.
Authenticated Traffic
Heavier user, can lead to more complex configurations to handle load and performance.
Caching for Drupal Websites
so here are five of the most important caching solutions for a Drupal website:
Drupal’s  built-in caching
Boost module
Memcached
Varnish
Views caching
There are other options, of course, but these five cover most of the ground. Let’s briefly go through them one at a time.
Drupal’s Built-in Caching
Most of a Drupal site is stored in the database – nodes, information about blocks, etc. – and enabling the default caching will store the results of these database queries so that they aren’t executed every time a page is requested. Enabling these settings alone can have a big impact on performance, particularly if your pages use a lot of views. This one is kind of a no-brainer.
Boost Module
The Boost module is pretty great. It works very well in tandem with Drupal caching, but it requires some additional configuration. What you end up with after you have the module installed and configured is a caching system that stores the output of your Drupal site as static HTML pages. This takes PHP processing out of the equation, leading to another nice bump in performance.
Memcached
Memcached can speed up dynamic applications (like Drupal) by storing objects in memory. With Boost and Drupal caching, the data being cached is stored on the server’s hard drive. With memcached, it’s being stored in memory instead of on the drive, something that can greatly speed up the response time for a page request.
Memcached works great in conjunction with both Boost and Drupal caching. For most folks, however, it’s something a server administrator will have to help install and configure.
Varnish
Varnish is an HTTP accelerator that, similar to memcached, stores data in memory. It’s capable of serving pages much faster than Apache (the most common web server for Drupal sites).
It can also be used in conjunction with memcached, although it’s often the case that they are not used together and other advanced caching methods are instead implemented alongside Varnish. Most people will need a server admin to help set up Varnish on their server.
Views Caching
Another type of database caching is Views caching. Views is a very popular, but rather resource intensive, Drupal module. Implementing Views caching can give your site a nice additional performance boost by possibly removing a few database queries from the build process.
To set views caching, go to your view. On the right hand side, under Advanced > Other, you’ll see a link for Caching. Just go in and set a value – an hour is usually a good default – for each view on your site.
Performance and Scalability in Drupal 7
Less SQL.
One of the most commonly mentioned performance issues in Drupal 5 and 6 was the number of queries executed per page, with most of these coming from path alias lookups. Path aliases allow a link to example.com/about to be converted to example.com/node/1 automatically in both directions. What is less known is that these queries were introduced in Drupal 4.7 to fix a scalability issue in earlier versions of Drupal.
Paths, round trips and mass transit
In Drupal 7 two large changes to the path system were introduced:
The path system maintains a white-list of which kinds of paths to look up aliases for, to avoid making round trips when there is nothing there to find – if there’s no aliases for user/*, it doesn’t bother looking for them.
Each page builds a cache of paths that were last requested, replaced every 24 hours or on cache clears. This allows those aliases to be queried in one go on the next request. If a path isn’t in the cache, it’s looked up individually until the next time the cache is refreshed.
The combination of these two optimizations means that on cache misses only a subset of paths are queried.
Entities on the wagon
In Drupal 7, introduced the Entity API and the concept of ‘multiple load’. The entity_load() function takes an array of entity IDs so database queries and hooks can all act on the list of entities at the same time. If a single node takes five database queries to build, it will only take five queries to build 30 nodes in Drupal 7, compared to 150 queries for the same objects in Drupal 6.
Big data, big queries
As Drupal has become more popular, the number of Drupal sites storing large amounts of data has increased. Drupal 7 introduces a number of measures to deal with this.
The new database layer and query builder allows drivers to specify case-insensitive operators. This allows MySQL to use LIKE() for auto-complete and user name lookups instead of LOWER(), allowing these queries to use indexes rather than doing a full table scan.
Forum, taxonomy and tracker modules now build de-normalized tables containing the data needed to build listings. Queries that used to require conditions and sorts across multiple tables can now be run against a single table, fully indexed.
InnoDB is enabled by default, providing much better safety and performance than MyISAM, particularly in situations with a large number of writes.
Fields and NoSQL
These de-normalized tables help with specific pain points encountered by Drupal 6 sites using those core features. However, a bigger issue facing Drupal sites is the combination of highly flexible storage via modules like CCK and Flag combined with the need to display that data in many different ways (often using the equally flexible Views module). This flexibility tends to lead to slow queries.
A plug for pluggability
In addition to the pluggable watchdog, cache and session backends in Drupal 6, Drupal 7 added pluggable lock and queue APIs. This means the storage for these systems can be moved out of SQL to MongoDB, Memcached, APC, Beanstalkd and other technologies better suited to handle these tasks at high volume.
Files and front end
Alongside swapping out SQL, Drupal 7 also allows you to swap out your local filesystem much easier, both for saving and serving files. Core file handling now uses PHP stream wrappers, meaning any file storage method supported by a stream wrapper can be used for file operations. Support already exists for Amazon S3 and the PHP hash wrapper in contributed modules. CDN support also got easier, with the CDN project providing drop-in support from contrib.
2) Explain panels and page layout ?

Features of Panels

  • Panels supports styles, which can control how individual content panes, regions within a panel, and the entire panel will be rendered. While Panels ships with few styles, styles can be provided as plugins by modules, as well as by themes!
  • The layout builder is nice for visually designing a layout, but a real HTML guru doesn’t want the somewhat weighty HTML that this will create. Modules and themes can provide custom layouts that can fit a designer’s exacting specifications, but still allow the site builder to place content wherever you like.
  • Panels includes a pluggable caching mechanism. A single cache type is included, the ‘simple’ cache which is time-based. Since most sites have very specific caching needs based upon the content and traffic patterns, this system was designed to let sites that need to devise their own triggers for cache clearing and implement plugins that will work with Panels. Panels can be cached as a whole, meaning the entire output of the panel can be cached, or individual content panes that are heavy can be cached.
  • Panels can be integrated with Organic Groups through the og_panels module to allow individual groups to have their own customized layouts.
  • Panels integrates with Views to allow administrators to add any view as content. Or, for uses where the layout editor needs more tightly controlled content, Views can be given custom displays to provide only what the site administrator wants the panels builder to use.

Panels module is a User Interface on top of theme() and hook_theme()
It’s very easy to get overwhelmed by the number of options, buttons and links. So let’s start simpler: a two column layout.
Explaining Panels blog post image
The code needed to declare that this two column layout exists at all is really small. Browse around the directory declaring it. There is not much there. An info array tells us most importantly that we have left and right regions.
‘regions’ => array(
‘left’ => t(‘Left side’),
‘right’ => t(‘Right side’)
),
And there’s a template file that prints the left and right regions.

>

</div>

</div>
</div>
Page Manager is a UI on top of hook_menu() and hook_menu_alter()
The response you get when visiting a URL on a Drupal site is determined largely by hook_menu(). When you go to the user register page you see a registration form because the user module told hook_menu() that a registration form belonged there. Other stuff may appear in Blocks in sidebars, footer and headers that are outside the knowledge of hook_menu(). hook_menu() primarily controls the main response that shows up in the “content” region of page.tpl.php
Here the distinction between Panels and Page Manager becomes cloudy. Page Manager tells Drupal “I know taxonomy module told you how term pages look, but I am overriding that. Use this Panels configuration instead.” Page Manager changes the way Drupal responds to existing paths as well as telling Drupal about new ones.
Panels is not even necessary to use Page Manager. Out of the box, Page Manager gives you the option to override existing URL paths just to change the HTTP response code (for that rare case where you want node/%node to respond with a 403 for anonymous users but don’t want to use the node access system). There are even other modules like Contextual Adminstration https://www.drupal.org/project/context_admin which use Page Manager to add more administrative options.
To go over that Jazz use case one more time, Page Manager:
Overrides the normal ‘list all nodes’ behavior declared by Taxonomy module.
Replaces it with a package of Panels configuration which
Declares the layout it wants
Contains instructions for populating the regions of that layout based on the given “context” (the taxonomy term “Jazz”)
Panels Everywhere is a UI alternative to page.tpl.php and Blocks UI
I just mentioned above that Page Manager is the way to control the the “content” region inside page.tpl.php. Panels Everywhere is meant to entirely replace your typical page.tpl.php customizations and the Block configurations that feed that file.
This block will show up on every page except those the pages whose URL paths match a certain pattern. Blocks can also be restricted by user role.
Mini Panels is a UI on top of individual Blocks If Panels Everywhere is a way to replace Core’s mechanism for organizing and displaying existing Blocks, Mini Panels is a way to add more individual Blocks. If you are writing a new Block with Core you will need a few pieces. You will need a machine name like “online” for the user module’s “Who’s online” block that lists currently logged in users, and you might need a configuration form for something like the number of users to show
Mini Panels allows you to accomplish those same concepts with less new code or no code at all. Mini Panels is perhaps the purest implementation of Panels in that it contains just the base concepts of Panels. You pick a layout plugin which is how the Mini Panel will actually render.
Panelizer is a (replacement) UI on top of View Modes Panelizer became famous/infamous in the Drupal community for the way it allows editors to make per-node overrides to Page Manager variants (which again almost always contain Panels configurations). Forget about that part for a moment. Panelizer has expanded its scope and is now best understood as a UI on top of View Modes. When you enable Panelizer it will give you a giant grid of checkboxes.
If you Panelize an article teaser view mode and you use Page Manager plus Panels to control the article listing URL and Panels Everywhere to control the global level then you’ll have three layers of Panels. Yes, you can do that.
http://www.palantir.net/blog/explaining-panels-overview-drupal-developers
3) DRUPAL 7 – how to create Sub themes ?
Creating a sub-theme is really simple. A sub-theme inherits a lot of the design resources from its parent theme. We can have multiple sub-themes inheriting only one base theme.
It is important to know that what a sub-theme inherits from its parent theme.
A sub theme will inherit:
All style sheets
Template files
Functions and overrides defined in the template.php
A sub-theme will not inherit:
Logos and Favicons
Block regions
Advanced theme settings
Creating a sub theme
Theme Directory: Create a directory in your custom theme directory in the same way you create a theme. Give it a name. For example: mysubtheme.
.info file: Create an .info file in the directory mysubtheme as similar to the parent theme. The only difference will be the following line:
base theme = theme_name
Logo: Add the logo in the sub-theme directory.
Screenshot: Theme screenshot is inherited from the base’s theme. To override the same, just create a new screenshot.png in the sub theme directory.
Style Sheets: You must declare at least one stylesheet in your sub-theme for any of the parent theme’s stylesheets to be inherited. To override any particular css file (for instance, style.css), add the following line in your .info file and add a new css file with the same name in your sub-theme’s directory.
stylesheets[all][] = style.css
Javascripts: All the js files defined in the parent theme will be inherited. To override any particular js file, add the following line in your .info file and add a new js file (for instance, script.js), with the same name in your sub-theme’s directory.
scripts[] = script.js
Regions: You can declare a new set of regions in the sub-theme. To inherit the custom regions of the parent theme, the regions should be copied in the sub-theme’s .info file.
Template Files: You can add any template files in your sub theme. If the template file is found in your sub-theme’s directory, then Drupal will override the parent’s template files. Otherwise, it will use the parent’s template files.
Images: The images used in the theme can also be copied in the sub theme directory. If the image is found in your sub-theme’s directory then Drupal will override the parent theme’s image with the same name. Otherwise, it will use the parent’s image.
4) explain Hooks and give any example worked on ?
Hooks are how modules can interact with the core code of Drupal. They make it possible for a module to define new urls and pages within the site (hook_menu), to add content to pages (hook_block, hook_footer, etc.), to set up custom database tables (hook_schema), and more. This page lists the hooks provided in the core, but modules can define hooks of their own. For example the cck module defines hook_field_info, which can be used by modules that want to define a new type of content field. Most modules that define hooks will also provide documentation about them.
A hook is a PHP function that can be called from Drupal, or third-party modules, when necessary to do a task. Instead of having a prefixed list of functions to call, the list is build checking the enabled modules, and the functions they implement.
For example, Drupal uses hook_node_update(); when a node is being saved with node_save(), the following code is executed.
// Call the node specific callback (if any). This can be
// node_invoke($node, ‘insert’) or
// node_invoke($node, ‘update’).
node_invoke($node, $op);
What node_invoke() does is the following:
Getting the list of all the enabled modules
Checking if the enabled modules has a function whose name ends in “_node_update” and starts with the short name of the module
Calling that function, passing $node as parameter
Hooks can save their own data in a database, or alter the value returned from a function. The last case is, for example, what happens with hook_form_alter(), which alters the value of $form passed as reference to drupal_prepare_form().
Drupal hooks are generally invoked using three functions:
drupal_alter()
module_invoke()
module_invoke_all()
drupal_alter() is the function used to invoke specific hooks whose purpose is to alter the data passed them as reference, such as hook_form_alter(), hook_hook_info_alter(), and hook_tokens_alter().
There are other functions that are used to invoke hooks, such as node_invoke(), but those functions essentially use one of the functions I listed before.
5) Explain DRUPAL bootstrap ?
Bootstrap is the process during the which Drupal initializes itself; the process actually includes:
Setting the error, and the exception handlers
Initializing the value of some spec-global variables contained in $_SERVER
Initializing some variables with init_set()
Finding the cached version of the page to serve
Initializing the database
Setting the handlers that load files when a class, or an interface is not found
Initializing the Drupal variables
Initializing the PHP session
Initializing the language variable
Loading the enabled modules
6) explain features ? How do features work?
The features module enables the capture and management of features in Drupal. A feature is a collection of Drupal entities which taken together satisfy a certain use-case.
Features provides a UI and API for taking different site building components from modules with exportables and bundling them together in a single feature module. A feature module is like any other Drupal module except that it declares its components (e.g. views, contexts, CCK fields, etc.) in its .info file so that it can be checked, updated, or reverted programmatically.
The purpose of the Features module is to copy configuration setups from one drupal site to another. It creates “packages” of the settings that can be shared among different sites. Today it is used in almost every development workflow to deploy changes from one environment to the other.
Assume that the developer creates a new content type and he wants to copy it to the development server. Here is what he will do with features:
1. He adds the content type to an existing feature (or creates a new one). features will automatically detect any dependencies (eg modules implementing the fields)
2. He downloads the features and copies it to the custom modules folder. Then he pushes it to the version control system.
3. The features module is pulled to the development site
4. The feature is enabled and the content type is automatically created.
Now assume that he makes some changes to the content type. Here is how he copies to changes to the site:
1. Updates the feature using the features UI or using drush (this causes the feature to pick up the changes)
2. Pushes the feature to the live site
3. He reverts the feature in the live site so that the changes are activated.
7) what are entitles and entitiy types?
An entity type is a useful abstraction to group together fields. Let’s consider some examples of entity types:
Nodes (content)
Comments
Taxonomy terms
User profiles
You can also build new kinds of entity types where the options above don’t suit your needs.
Bundles
Bundles are an implementation of an entity type to which fields can be attached. You can consider bundles as subtypes of an entity type. With content nodes (an entity type), for example, you can generate bundles (subtypes) like articles, blog posts, or products. Not all entity types have bundles, however. For example, users do not have separate bundles (subtypes). For the entity types that do allow bundles, you can create as many bundles (subtypes) as you want. Then, using the Field system, you can add different fields to each bundle. Examples include a file download field on Basic Pages and a subtitle field on Articles.
Fields
A field is a reusable piece of content. In technical terms, each field is a primitive data type, with custom validators and widgets for editing and formatters for display.
Entity
An entity would be one instance of a particular entity type such as a comment, taxonomy term or user profile or a bundle such as a blog post, article or product.
You can use entity_load to load any entity. Note, however, that the core does not provide a save or delete function, but thanks to Entity API module the missing pieces are added (entity_create(), entity_save(), entity_delete(), entity_view() and entity_access()).
Entity API module
The project Entity API extends the entity API of Drupal core in order to provide a unified way to deal with entities and their properties. Additionally, it provides an entity CRUD controller, which helps in simplifying the creation of new entity types.
Putting this in Object-Oriented Design/Programming terms
An entity type is a base class
A bundle is an extended class
A field is a class member, property, variable or field instance (depending on your naming preference)
An entity is an object or instance of a base or extended class
8)Multi Language translation in DRUPAL ?
There are two basic components to the translation system, the translation of the interface and the translation of content.
Translating the interface has to do with the translation of miscellaneous text strings used all over the site (like the label used on Submit buttons). These are elements that are the same on all sites no matter what actual content it contains. Because these strings are standardized, Drupal is able to create a system to provide everyone with translated values for all these elements in various languages. To take advantage of this you enable the core Locale module, which will allow you to grab translated text from the Drupal Localizer site and import them into your site
Content Translation
in earlier versions of Drupal by creating a complete copy of each node that needs translation. So the French node would have all the French values of the content and the English node would have all the English values. Then they are organized together in translation sets.
it is still available in Drupal 7, if you enable the core Content Translation module.
Entity Translation
In Drupal 7, a new model for content translation was created. In this system each piece of content consists of a single node, but each field on the node can have multiple copies, in different languages, all attached to the same entity.
The API to get this system working went into core, but there was no time (and not enough agreement) to get a UI into core. So the Entity Translation module was created to provide a way for site administrators and translators to use the new field translation system.
Creating a Site Using Entity Translation
The minimum list of modules we will need include:
Locale (included in core)
Entity Translation
Title (to translate the node titles)
Entity (required by Title)
To add some usability to the site, we’ll also use:
Internationalization (i18n)
Variable (required by many of the translation modules)
Localization Update
Language Icons

Categories
AJAX CSS LAMP MySQL PHP XML

MNC php interview questions and answers

1) what is session_set_save_handler in PHP? session_set_save_handler() sets the user-level session storage functions which are used for storing and retrieving data associated with a session. This is most useful when a storage method other than those supplied by PHP sessions is preferred. i.e. Storing the session data in a local database.

2) what is garbage collection? default time ? refresh time? Garbage Collection is an automated part of PHP , If the Garbage Collection process runs, it then analyzes any files in the /tmp for any session files that have not been accessed in a certain amount of time and physically deletes them. arbage Collection process only runs in the default session save directory, which is /tmp. If you opt to save your sessions in a different directory, the Garbage Collection process will ignore it. the Garbage Collection process does not differentiate between which sessions belong to whom when run. This is especially important note on shared web servers. If the process is run, it deletes ALL files that have not been accessed in the directory.

There are 3 PHP.ini variables, which deal with the garbage collector: PHP ini  value

name                                          default

session.gc_maxlifetime     1440 seconds or 24 minutes

session.gc_probability      1

session.gc_divisor              100

3) PHP how to know user has read the email? Using Disposition-Notification-To: in mailheader we can get read receipt.

Add the possibility to define a read receipt when sending an email.

It’s quite straightforward, just edit email.php, and add this at vars definitions:

var $readReceipt = null;

And then, at ‘createHeader’ function add:

if (!empty($this->readReceipt)) { $this->__header .= ‘Disposition-Notification-To: ‘ . $this->__formatAddress($this->readReceipt) . $this->_newLine; }

4) Runtime library loading ? without default mysql support, how to run mysql with php?

dl — Loads a PHP extension at runtime int dl ( string $library )

Loads the PHP extension given by the parameter library .

Use extension_loaded() to test whether a given extension is already available or not. This works on both built-in extensions and dynamically loaded ones (either through php.ini or dl()).

bool extension_loaded ( string $name ) — Find out whether an extension is loaded

Warning :This function has been removed from some SAPI’s in PHP 5.3.

5) what is XML-RPC ? XML-RPC is a remote procedure call protocol which uses XML to encode its calls and HTTP as a transport mechanism. An XML-RPC message is an HTTP-POST request. The body of the request is in XML. A procedure executes on the server and the value it returns is also formatted in XML.

6) default session time ? default session time in PHP is 1440 seconds or 24 minutes.

7) default session save path ? Default session save path id temporary folder /tmp

8) What is the difference between htmlentities() and htmlspecialchars()?

htmlspecialchars() – Convert some special characters to HTML entities (Only the most widely used) htmlentities() – Convert ALL special characters to HTML entities

9) how to do session using DB?

bool session_set_save_handler ( callback $open , callback $close , callback $read , callback $write , callback $destroy , callback $gc ) using this function we can store sessions in DB.

PHP has a built-in ability to override its default session handling. The function session_set_save_handler() lets the programmer specify which functions should actually be called when it is time to read or write session information. by overriding the default functions using session_set_save_handler handle we can store session in Db like below example

class SessionManager {

var $life_time;

function SessionManager() {

// Read the maxlifetime setting from PHP $this->life_time = get_cfg_var(“session.gc_maxlifetime”);

// Register this object as the session handler session_set_save_handler( array( &$this, “open” ), array( &$this, “close” ), array( &$this, “read” ), array( &$this, “write”), array( &$this, “destroy”), array( &$this, “gc” ) );

}

function open( $save_path, $session_name ) {

global $sess_save_path;

$sess_save_path = $save_path;

// Don’t need to do anything. Just return TRUE.

return true;

}

function close() {

return true;

}

function read( $id ) {

// Set empty result $data = ”;

// Fetch session data from the selected database

$time = time();

$newid = mysql_real_escape_string($id); $sql = “SELECT `session_data` FROM `sessions` WHERE `session_id` = ‘$newid’ AND `expires` > $time”;

$rs = db_query($sql); $a = db_num_rows($rs);

if($a > 0) { $row = db_fetch_assoc($rs); $data = $row[‘session_data’];

}

return $data;

}

function write( $id, $data ) {

// Build query $time = time() + $this->life_time;

$newid = mysql_real_escape_string($id); $newdata = mysql_real_escape_string($data);

$sql = “REPLACE `sessions` (`session_id`,`session_data`,`expires`) VALUES(‘$newid’, ‘$newdata’, $time)”;

$rs = db_query($sql);

return TRUE;

}

function destroy( $id ) {

// Build query $newid = mysql_real_escape_string($id); $sql = “DELETE FROM `sessions` WHERE `session_id` = ‘$newid'”;

db_query($sql);

return TRUE;

}

function gc() {

// Garbage Collection

// Build DELETE query. Delete all records who have passed the expiration time $sql = ‘DELETE FROM `sessions` WHERE `expires` < UNIX_TIMESTAMP();’;

db_query($sql);

// Always return TRUE return true;

}

}

10) how to track user logged out or not? when user is idle ? By checking the session variable exist or not while loading th page. As the session will exist longer as till browser closes.

The default behaviour for sessions is to keep a session open indefinitely and only to expire a session when the browser is closed. This behaviour can be changed in the php.ini file by altering the line session.cookie_lifetime = 0 to a value in seconds. If you wanted the session to finish in 5 minutes you would set this to session.cookie_lifetime = 300 and restart your httpd server.

11) how to track no of user logged in ? whenever a user logs in track the IP, userID etc..and store it in a DB with a active flag while log out or sesion expire make it inactive. At any time by counting the no: of active records we can get the no: of visitors.

12) in PHP for pdf which library used?

The PDF functions in PHP can create PDF files using the PDFlib library With version 6, PDFlib offers an object-oriented API for PHP 5 in addition to the function-oriented API for PHP 4. There is also the » Panda module.

FPDF is a PHP class which allows to generate PDF files with pure PHP, that is to say without using the PDFlib library. F from FPDF stands for Free: you may use it for any kind of usage and modify it to suit your needs.

FPDF requires no extension (except zlib to activate compression and GD for GIF support) and works with PHP4 and PHP5.

13) for image work which library?

You will need to compile PHP with the GD library of image functions for this to work. GD and PHP may also require other libraries, depending on which image formats you want to work with.

14) what is oops? encapsulation? abstract class? interface?

Object oriented programming language allows concepts such as modularity, encapsulation, polymorphism and inheritance.

Encapsulation passes the message without revealing the exact functional details of the class. It allows only the relevant information to the user without revealing the functional mechanism through which a particular class had functioned.

Abstract class is a template class that contains such things as variable declarations and methods, but cannot contain code for creating new instances. A class that contains one or more methods that are declared but not implemented and defined as abstract. Abstract class: abstract classes are the class where one or more methods are abstract but not necessarily all method has to be abstract. Abstract methods are the methods, which are declare in its class but not define. The definition of those methods must be in its extending class.

Interface: Interfaces are one type of class where all the methods are abstract. That means all the methods only declared but not defined. All the methods must be define by its implemented class.

15) what is design pattern? singleton pattern?

A design pattern is a general reusable solution to a commonly occurring problem in software design.

The Singleton design pattern allows many parts of a program to share a single resource without having to work out the details of the sharing themselves.

16) what are magic methods?

Magic methods are the members functions that is available to all the instance of class Magic methods always starts with “__”. Eg. __construct All magic methods needs to be declared as public To use magic method they should be defined within the class or program scope Various Magic Methods used in PHP 5 are: __construct() __destruct() __set() __get() __call() __toString() __sleep() __wakeup() __isset() __unset() __autoload() __clone()

17) what is magic quotes? Magic Quotes is a process that automagically escapes incoming data to the PHP script. It’s preferred to code with magic quotes off and to instead escape the data at runtime, as needed. This feature has been DEPRECATED as of PHP 5.3.0 and REMOVED as of PHP 6.0.0. Relying on this feature is highly discouraged.

18) diff b/w php4 & php5 ? In PHP5 1 Implementation of exceptions and exception handling

2. Type hinting which allows you to force the type of a specific argument as object, array or NULL

3. Overloading of methods through the __call function

4. Full constructors and destructors etc through a __constuctor and __destructor function

5. __autoload function for dynamically including certain include files depending on the class you are trying to create.

6 Finality : can now use the final keyword to indicate that a method cannot be overridden by a child. You can also declare an entire class as final which prevents it from having any children at all.

7 Interfaces & Abstract Classes

8 Passed by Reference : In PHP4, everything was passed by value, including objects. This has changed in PHP5 — all objects are now passed by reference.

9 An __clone method if you really want to duplicate an object

19) in php4 can you define a class? how to call class in php4? can you create object in php4?

yes you can define class and can call class by creating object of that class. but the diff b/w php4 & php5 is that in php4 everything was passed by value where as in php5 its by reference. And also any value change in reference object changes the actucal value of object also. And one more thing in introduction of __clone object in PHP5 for copying the object.

20) types of error? how to set error settings at run time?

here are three basic types of runtime errors in PHP:

1. Notices: These are trivial, non-critical errors that PHP encounters while executing a script – for example, accessing a variable that has not yet been defined. By default, such errors are not displayed to the user at all – although you can change this default behaviour.

2. Warnings: These are more serious errors – for example, attempting to include() a file which does not exist. By default, these errors are displayed to the user, but they do not result in script termination.

3. Fatal errors: These are critical errors – for example, instantiating an object of a non-existent class, or calling a non-existent function. These errors cause the immediate termination of the script, and PHP?s default behaviour is to display them to the user when they take place.

by using ini_set function.

21) what is cross site scripting? SQL injection?

Cross-site scripting (XSS) is a type of computer security vulnerability typically found in web applications which allow code injection by malicious web users into the web pages viewed by other users. Examples of such code include HTML code and client-side scripts.

SQL injection is a code injection technique that exploits a security vulnerability occurring in the database layer of an application. The vulnerability is present when user input is either incorrectly filtered for string literal escape characters embedded in SQL statements or user input is not strongly typed and thereby unexpectedly executed

22) what is outerjoin? inner join?

OUTER JOIN in SQL allows us to retrieve all values in a certain table regardless of whether these values are present in other tables

An inner join requires each record in the two joined tables to have a matching record. An inner join essentially combines the records from two tables (A and B) based on a given join-predicate.

23) what is URL rewriting?

Using URL rewriting we can convert dynamic URl to static URL Static URLs are known to be better than Dynamic URLs because of a number of reasons 1. Static URLs typically Rank better in Search Engines. 2. Search Engines are known to index the content of dynamic pages a lot slower compared to static pages. 3. Static URLs are always more friendlier looking to the End Users.

along with this we can use URL rewriting in adding variables [cookies] to the URL to handle the sessions.

24) what is the major php security hole? how to avoid?

1. Never include, require, or otherwise open a file with a filename based on user input, without thoroughly checking it first. 2. Be careful with eval() Placing user-inputted values into the eval() function can be extremely dangerous. You essentially give the malicious user the ability to execute any command he or she wishes! 3. Be careful when using register_globals = ON It was originally designed to make programming in PHP easier (and that it did), but misuse of it often led to security holes 4. Never run unescaped queries 5. For protected areas, use sessions or validate the login every time. 6. If you don’t want the file contents to be seen, give the file a .php extension.

25) whether PHP supports Microsoft SQL server ? The SQL Server Driver for PHP v1.0 is designed to enable reliable, scalable integration with SQL Server for PHP applications deployed on the Windows platform. The Driver for PHP is a PHP 5 extension that allows the reading and writing of SQL Server data from within PHP scripts. using MSSQL or ODBC modules we can access Microsoft SQL server.

26) what is MVC? why its been used? Model-view-controller (MVC) is an architectural pattern used in software engineering. Successful use of the pattern isolates business logic from user interface considerations, resulting in an application where it is easier to modify either the visual appearance of the application or the underlying business rules without affecting the other. In MVC, the model represents the information (the data) of the application; the view corresponds to elements of the user interface such as text, checkbox items, and so forth; and the controller manages the communication of data and the business rules used to manipulate the data to and from the model.

WHY ITS NEEDED IS 1 Modular separation of function 2 Easier to maintain 3 View-Controller separation means:

A — Tweaking design (HTML) without altering code B — Web design staff can modify UI without understanding code

27) what is framework? how it works? what is advantage?

In general, a framework is a real or conceptual structure intended to serve as a support or guide for the building of something that expands the structure into something useful. Advantages : Consistent Programming Model Direct Support for Security Simplified Development Efforts Easy Application Deployment and Maintenance

28) what is CURL?

CURL means Client URL Library

curl is a command line tool for transferring files with URL syntax, supporting FTP, FTPS, HTTP, HTTPS, SCP, SFTP, TFTP, TELNET, DICT, LDAP, LDAPS and FILE. curl supports SSL certificates, HTTP POST, HTTP PUT, FTP uploading, HTTP form based upload, proxies, cookies, user+password authentication (Basic, Digest, NTLM, Negotiate, kerberos…), file transfer resume, proxy tunneling and a busload of other useful tricks.

CURL allows you to connect and communicate to many different types of servers with many different types of protocols. libcurl currently supports the http, https, ftp, gopher, telnet, dict, file, and ldap protocols. libcurl also supports HTTPS certificates, HTTP POST, HTTP PUT, FTP uploading (this can also be done with PHP’s ftp extension), HTTP form based upload, proxies, cookies, and user+password authentication.

29) HOW we can transfer files from one server to another server without web forms?

using CURL we can transfer files from one server to another server. ex:

Uploading file

<?php

/* http://localhost/upload.php: print_r($_POST); print_r($_FILES); */

$ch = curl_init();

$data = array(‘name’ => ‘Foo’, ‘file’ => ‘@/home/user/test.png’);

curl_setopt($ch, CURLOPT_URL, ‘http://localhost/upload.php’);

curl_setopt($ch, CURLOPT_POST, 1); curl_setopt($ch, CURLOPT_POSTFIELDS, $data);

curl_exec($ch); ?>

output:

Array ( [name] => Foo ) Array ( [file] => Array ( [name] => test.png
[type] => image/png [tmp_name] => /tmp/phpcpjNeQ [error] => 0 [size] => 279 )   )
  30) using CSS can we have a scroll to table? 
No table won't support scrolling of its data. but we can do another workaround like placing a table
 in a DIV  layer and setting the DIV css property to overflow:auto will do the trick.
  31) how to increase session time in PHP ? 
In php.ini by setting session.gc_maxlifetime and session.cookie_lifetime values
we can change the session time in PHP.   
 32) what is UI? What are the five primary user-interface components?  
 A user interface is a means for human beings to interact with computer-based "tools" and"messages".
One presumed goal is to make the user's experience productive, efficient, pleasing, and humane.
 The primary components of UIs are  a) metaphors (fundamental concepts communicated
 through words, images, sounds, etc.)
b) mental models (structure of data, functions, tasks, roles, jobs, and people in organizations of work
and/or play)
 c) navigation (the process of moving through the mental models)
d) interaction (all input-output sequences and means for conveying feedback)
 e) and appearance (visual, verbal, acoustic, etc.).
33) How can I set a cron and how can I execute it in Unix, Linux, and windows?

Cron is very simply a Linux module that allows you to run commands at predetermined times or intervals.
In Windows, it’s called Scheduled Tasks. The name Cron is in fact derived from the same word from which we get the word chronology, which means order of time.
The easiest way to use crontab is via the crontab command. # crontab This command ‘edits’ the crontab.
Upon employing this command, you will be able to enter the commands that you wish to run.
My version of Linux uses the text editor vi. You can find information on using vi here.
The syntax of this file is very important – if you get it wrong, your crontab will not function properly.
The syntax of the file should be as follows: minutes hours day_of_month month day_of_week command All the variables, with the exception of the command itself, are numerical constants.
In addition to an asterisk (*), which is a wildcard that allows any value, the ranges permitted for each field are as follows: Minutes: 0-59 Hours: 0-23 Day_of_month: 1-31 Month: 1-12 Weekday: 0-6 We can also include multiple values for each entry, simply by separating each value with a comma.
command can be any shell command and, as we will see momentarily, can also be used to execute a Web document such as a PHP file. So, if we want to run a script every Tuesday morning at 8:15 AM, our mycronjob file will contain the following content on a single line: 15 8 * * 2 /path/to/scriptname This all seems simple enough, right? Not so fast! If you try to run a PHP script in this manner, nothing will happen (barring very special configurations that have PHP compiled as an executable, as opposed to an Apache module).
The reason is that, in order for PHP to be parsed, it needs to be passed through Apache. In other words, the page needs to be called via a browser or other means of retrieving Web content.
For our purposes, I’ll assume that your server configuration includes wget, as is the case with most default configurations. To test your configuration, log in to shell.
If you’re using an RPM-based system (e.g. Redhat or Mandrake), type the following: # wget help If you are greeted with a wget package identification, it is installed in your system.
You could execute the PHP by invoking wget on the URL to the page, like so: # wget http://www.example.com/file.php Now, let’s go back to the mailstock.php file we created in the first part of this article.
We saved it in our document root, so it should be accessible via the Internet. Remember that we wanted it to run at 4PM Eastern time, and send you your precious closing bell report? Since I’m located in the Eastern timezone, we can go ahead and set up our crontab to use 4:00, but if you live elsewhere, you might have to compensate for the time difference when setting this value.
This is what my crontab will look like: 0 4 * * 1,2,3,4,5 wget http://www.example.com/mailstock.php
34)Difference b/w OOPS concept in php4 and PHP5 ?
version 4’s object-oriented functionality was rather hobbled. Although the very basic premises of objectoriented programming (OOP) were offered in version 4, several deficiencies existed, including: • An unorthodox object-referencing methodology • No means for setting the scope (public, private, protected, abstract) of fields and methods • No standard convention for naming constructors • Absence of object destructors • Lack of an object-cloning feature • Lack of support for interfaces
35) Difference b/w MyISAM and InnoDB in MySQL?
Ans:

  • The big difference between MySQL Table Type MyISAM and InnoDB is that InnoDB supports transaction
  • InnoDB supports some newer features: Transactions, row-level locking, foreign keys
  • InnoDB is for high volume, high performance
  • use MyISAM if they need speed and InnoDB for data integrity.
  • InnoDB has been designed for maximum performance when processing large data volumes
  • Even though MyISAM is faster than InnoDB
  • InnoDB supports transaction. You can commit and rollback with InnoDB but with MyISAM once you issue a command it’s done
  • MyISAM does not support foreign keys where as InnoDB supports
  • Fully integrated with MySQL Server, the InnoDB storage engine maintains its own buffer pool for caching data and indexes in main memory. InnoDB stores its tables and indexes in a tablespace, which may consist of several files (or raw disk partitions). This is different from, for example, MyISAM tables where each table is stored using separate files. InnoDB tables can be of any size even on operating systems where file size is limited to 2GB.
  • 36) how to set session tiem out at run time or how to extend the session timeout at runtime?
    Ans:
    Sometimes it is necessary to set the default timeout period for PHP. To find out what the default (file-based-sessions) session timeout value on the server is you can view it through a ini_get command:

    // Get the current Session Timeout Value
    $currentTimeoutInSecs = ini_get(’session.gc_maxlifetime’);

    Change the Session Timeout Value

    // Change the session timeout value to 30 minutes
    ini_set(’session.gc_maxlifetime’, 30*60);

    If you have changed the sessions to be placed inside a Database occasionally implementations will specify the expiry manually. You may need to check through the session management class and see if it is getting the session timeout value from the ini configuration or through a method parameter (with default). It may require a little hunting about.

    Categories
    LAMP MySQL PHP

    Aztecsoft php web developer interview questions and answers

    1) how to increase the web page performance ?
    1) Use lightweight templates
    2) Put Stylesheets at the Top
    3) Put Scripts at the Bottom
    4) Avoid CSS Expressions like As an example, the background color could be set to alternate every hour using CSS expressions.
    background-color: expression( (new Date()).getHours()%2 ? “#B8D4FF” : “#F08A00” );
    5) Make JavaScript and CSS External
    6) Minify JavaScript and CSS : Minification is the practice of removing unnecessary characters from code to reduce its size thereby improving load times.
    7) Remove Duplicate Scripts
    8) Choose over @import
    9) Don’t Scale Images in HTML
    10) Make favicon.ico Small and Cacheable
    11) use Ajax, JSON, Jquery for fastening results
     
    2) $test=array( 0=>’one’ , 2=> ‘two’ , ‘3 ‘=>’three’ , ‘3a’=>5, ‘myindex’); print_r($test); what will be the output? 
    Array ( [0] => one [2] => two [3 ] => three [3a] => 5 [3] => myindex )
    3) what is output of this mysql function select substring_index(‘abc@123.com’,”@”,-1); 
    Ans:  123.com   explanation is below
    SUBSTRING_INDEX(str,delim,count)

    Returns the substring from string str before count occurrences of the delimiter delim. If count is positive, everything to the left of the final delimiter (counting from the left) is returned. If count is negative, everything to the right of the final delimiter (counting from the right) is returned. SUBSTRING_INDEX() performs a case-sensitive match when searching for delim.

    mysql> SELECT SUBSTRING_INDEX('www.mysql.com', '.', 2);
            -> 'www.mysql'
    mysql> SELECT SUBSTRING_INDEX('www.mysql.com', '.', -2);
            -> 'mysql.com'

    This function is multi-byte safe.
     
    4) An employee table having columns  id {employee id} , name {employee name},  m_id {manager id }  , write a query to select employee and their manager names  ? 
     

    Main table    
    id name m_id
    1 John 2
    2 Greek Tor 1
    3 Alex John 1
    4 Mike tour 1
    5 Brain J 3
    6 Ronald 3
    7 Kin 4
    8 Herod 3
    9 Alen 2
    10 Ronne 1

    Ans:  INNER join SQL command is mostly used to join one table to it self. The biggest advantage of doing this is to get linking information from the same table. We will try to understand this with an example. The best example of INNER join will be employee table where we will keep the employee and its manager as a single record. This way by linking to the table it self we will generate a report displaying it as two linked tables. Each record will have one additional field storing the data of the manager by keeping the employee ID and we will use M_ID ( manager ID ) to link with main employee ID. This way we will link two virtual tables generated from one main table. 
    let us use inner join to create one report on who is the manager of which employee. Check this SQL 
    SELECT t1.id, t1.name as emp_name, t2.name as manager FROM emp as t1 INNER JOIN emp as t2 on t2.id = t1.m_id

    id emp_name manager
    1 John Greek Tor
    2 Greek Tor John
    3 Alex John John
    4 Mike tour John
    5 Brain J Alex John
    6 Ronald Alex John
    7 Kin Mike tour
    8 Herod Alex John
    9 Alen Greek Tor
    10 Ronne John

    for more :  To generate only the manager table used this SQL
    SELECT t1.id,t1.name as emp_name from emp as t1 INNER JOIN emp as t2 on t1.id=t2.m_id 
    Managers Table
     

     
    id emp_name
    2 Greek Tor
    1 John
    1 John
    1 John
    3 Alex John
    3 Alex John
    4 Mike tour
    3 Alex John
    2 Greek Tor
    1 John

     
    To generate only the employee table  used this SQL
    SELECT t1.id,t1.name as emp_name from emp as t1 INNER JOIN emp as t2 on t2.id=t1.m_id 

       
    id emp_name
    1 John
    2 Greek Tor
    3 Alex John
    4 Mike tour
    5 Brain J
    6 Ronald
    7 Kin
    8 Herod
    9 Alen
    10 Ronne

     
    use below dump for your reference 
    CREATE TABLE `emp` (
    `id` int(4) NOT NULL auto_increment,
    `name` varchar(25) NOT NULL default ”,
    `m_id` int(4) NOT NULL default ‘0’,
    UNIQUE KEY `id` (`id`)
    ) ENGINE=MyISAM AUTO_INCREMENT=11 DEFAULT CHARSET=latin1 AUTO_INCREMENT=11 ;
    — 
    — Dumping data for table `emp`
    — 
    INSERT INTO `emp` VALUES (1, ‘John’, 2);
    INSERT INTO `emp` VALUES (2, ‘Greek Tor’, 1);
    INSERT INTO `emp` VALUES (3, ‘Alex John’, 1);
    INSERT INTO `emp` VALUES (4, ‘Mike tour’, 1);
    INSERT INTO `emp` VALUES (5, ‘Brain J’, 3);
    INSERT INTO `emp` VALUES (6, ‘Ronald’, 3);
    INSERT INTO `emp` VALUES (7, ‘Kin’, 4);
    INSERT INTO `emp` VALUES (8, ‘Herod’, 3);
    INSERT INTO `emp` VALUES (9, ‘Alen’, 2);
    INSERT INTO `emp` VALUES (10, ‘Ronne’, 1);


    5) write code to read the following file content “rag.txt”  and replace postgre SQL to MySQL and output the content ?
    The postgre SQL database has become the world’s most popular open source database because of its consistent fast performance, high reliability and ease of use. postgre SQL used on every continent — Yes, even Antarctica! — by individual Web developers as well as many of the world’s largest and fastest-growing organizations to save time and money powering their high-volume Web sites, business-critical systems and packaged software by postgre SQL.
    Ans:
     $str = file_get_contents(‘rag.txt’);
    $str = str_replace(‘postgre SQL’ ,’MySQL’, $str);
    echo $str;
     
    6) how we can destroy session cookie?
    Ans: we can use session_destroy() or  to destroy particular cookie set it to past time using  setcookie () function like  setcookie (“TestCookie”“”time() – 3600);
    7) True or False 
    a) session_destroy()  : destroys all of the data from session   TRUE
    b) session_unset() : frees all session variable  TRUE

    c) unset($_SESSION) deletes all session data   FALSE    “Do NOT unset the whole $_SESSION with unset($_SESSION) as this will disable the registering of session variables through the $_SESSION superglobal.”  

    8) $array = array( “hi”, “Hello World” , “what”, “Good Morning”);  write code to output the array contents havng more than one word ?
    Ans: 
        

    <? $array = array( “hi”, “Hello World” , “what”, “Good Morning”); 
    $count = sizeof($array);
    $i =0;
    while ($i < $count )
    {
    echo “<br> ***********<br>”;
    $exp = explode ( ” ” ,$array[$i] );
    if (count($exp) > 1)
    echo $array[$i] .” is having more than  one word in “. $i.” position of array  <br>”;
    $i++;
    }
    ?>
    9) what is the output of the below code 
    $sec_array = array(“red”, “green”, “blue”,”yellow”);
    array_splice( $sec_array , 1, -1);
    print_r($sec_array );   ? 

     

    Ans: Array ( [0] => red [1] => yellow )
    10) how we can get the second value from the last in an array ?
    Ans: 
    example  <? 
    $check = array ( “rag”, “shara”, “sharag”, “man”,”woman”,”child”, “human”);
    echo $check[count($check)-2];
    ?>

    11)  What is the maximum length of a URL?
    Microsoft states that the maximum length of a URL in Internet Explorer is 2,083 characters, with no more than 2,048 characters in the path portion of the URL
    Firefox, Safari , Opera  supports more than 100,000 characters.  but some times server like Apache, IIS may not support these longer URL’s. so better to keep it short URL.


    Categories
    LAMP MySQL PHP

    PHP common interview questions – answers

    =,==,=== – what is the difference between these?
    = assigns a value, == checks if value is the same, === checks if value is the same and the variables are of the exact same type.
    Echo, print, printf – what is the difference between these?
    Print and echo both output what is passed to them. Print acts like a function, so you can use it in complex statements. Printf is used to format the output.
    Include, include once, require – what is the difference between these?
    Include will includes a file each time it is called. Include_once would only include a file one time, so if a php program has a file in two include_once statements only the first will be done. Requre is like include, but if the file included is not available a fatal error occurs and processing stops.
    Are variables passed to functions by reference or value?
    A variable is passed by value unless the variable is passed with an &, such as functionName(&$variableName)
    How do you encrypt data?
    The PHP md5() function is very pretty widely used. The PHP crypt() function can also be used to encrypt data. (Honestly, the one time I had this question I drew a complete blank, so I’m not exactly certain what they were looking for.)
    What editor or ide do you use?
    Interesting question, probably does say something about your programming capabilites.  use Eclipse 3.1 with PHP extensions, , Zend Studio  Serious Unix users would be good with vi or emacs.
    PHP  Static, what are they and how do you use them?
    As with Java, if the job is for OO PHP (that is PHP 5), there will be a question on PHP static variables. You may be asked how to reference a static from inside and outside of the class it is in, or just show that you get the basic concept of a variable or function that is for the whole class and not an instance.
    Design Patterns general questions
    Now we are really into OO stuff. As in java job interviews I’ve usually been asked about design patterns in fairly vague terms, such as “describe the design patterns used in the systems you have worked on”. I was asked that so much that I drew out some UML to bring with me to interviews, as I found drawing up the UML during the interview to be distracting and slow.
    How can I maintain the count of how many persons have hit my site?
    The IP of a visitor can be tracked by
    $ip = $_SERVER[‘REMOTE_ADDR’];
    Just insert this value with date into a table.
    What is difference between mysql_fetch_array(), mysql_fetch_row() and mysql_fetch_object()?
    mysql_fetch_array()– Fetche resultset from a table in the form of array
    Eg: $res= mysql_query(’select * from tbl’)
    while ($row=mysql_fetch_array($res))
    mysql_fetch_row()
    Fetch single row
    mysql_fetch_object()
    Fetches resultset as object
    How I can make a chat page in php in simple
    On click on chat submit button store the values in the text area to a text file using PHP file functions.
    you can use ajax fore improved user experiance.
    wrie another javascript + ajax function to call the contents from the text file in each 3 sec


     
    What is the difference between echo and print statement?
    Print is a function and returns a value. Using echo we can use more than one parameter
    echo “and a “, 1, 2, 3; 
    What is differenc between mysql_connect and mysql_pconnect?
    mysql_connect- Creates a connection with db
    mysql_pconnect- creates a persistant connection with db 
    How I can get IP address of the user?
    )$ip = $_SERVER[‘REMOTE_ADDR’]; 
    How I will check that user is logged in or not?
    store user information in session

    I want to make it a function and I want to use it in each page and after login I want to go in current page?
    )store url in a variable and put in session before
    After login redirect page to that url 
    How do we know browser properties?
    var_dump($_SERVER); 
    If you have to work with dates in the following format: “Tuesday, February 14, 2006 @ 10:39 am”, how can you convert them to another format, that is easier to use?
    first remove @ from the string and than use strtime to convert this to unix time stamp.
    What is difference between require_once(), require(), include()?
    all are for including afile into another file
    require- if fails shoot a fatal error
    include- if fails shoot a warning
    include/require_once- for make sure that the page is included once in another page

    Categories
    MySQL PHP

    important PHP interview questions and answers

    Here is some PHP Interview Questions, that will helpfull to PHP Interview Candidates
    1. What is CAPTCHA?
    CAPTCHA stands for Completely Automated Public Turing Test to tell Computers and Humans Apart. To prevent spammers from using bots to automatically fill out forms, CAPTCHA programmers will generate an image containing distorted images of a string of numbers and letters. Computers cannot determine what the numbers and letters are from the image but humans have great pattern recognition abilities and will be able to fairly accurately determine the string of numbers and letters. By entering the numbers and letters from the image in the validation field, the application can be fairly assured that there is a human client using it. To read more look here:
    http://en.wikipedia.org/wiki/Captcha
    2. What is difference between require_once(), require(), include().
    Becouse above three function usely use to call a file in another file?

    Difference between require() and require_once(): require() includes and evaluates a specific file, while require_once() does that only if it has not been included before (on the same page). So, require_once() is recommended to use when you want to include a file where you have a lot of functions for example. This way you make sure you don’t include the file more times and you will not get the “function re-declared” error. Difference between require() and include() is that require() produces a FATAL ERROR if the file you want to include is not found, while include() only produces a WARNING. There is also include_once() which is the same as include(), but the difference between them is the same as the difference between require() and require_once().
    3. If you have to work with dates in the following format: “Tuesday, February 14, 2006 @ 10:39 am”, how can you convert them to another format, that is easier to use?
    The strtotime function can convert a string to a timestamp. A timestamp can be converted to date format. So it is best to store the dates as timestamp in the database, and just output them in the format you like.
    So let’s say we have
    $date = “Tuesday, February 14, 2006 @ 10:39 am”;
    In order to convert that to a timestamp, we need to get rid of the “@” sign, and we can use the remaining string as a parameter for the strtotime function.
    So we have
    $date = str_replace(“@ “,””,$date);
    $date = strtotime($date);
    now $date is a timestamp
    and we can say:
    echo date(“d M Y”,$date);
    4. How we know browser properties?
    get_browser() attempts to determine the capabilities of the user’s browser. This is done by looking up the browser’s information in the browscap.ini file.
    echo $_SERVER[‘HTTP_USER_AGENT’] . ”


    \n”;
    $browser = get_browser();
    foreach ($browser as $name => $value) {
    echo “$name $value
    \n”;
    }
    5. How i will check that user is, logged in or not. i want to make it a function and i want to use in each page and after login i want to go in current page(same page. where i was working)?
    For this we can use the session objec($_SESSION)t. When the user login with his/ her user name and password, usually we check those to ensure for correctness. If that user name and password are valid one then we can store that user name in a session and then we can very that session variable has been set or not in a single files and we can include that file in all pages.
    6. How i can get ip address?
    We can use SERVER var $_SERVER[‘SERVER_ADDR’] and getenv(“REMOTE_ADDR”) functions to get the IP address.
    7. What is difference between mysql_connect and mysql_pconnect?
    mysql_pconnect establishes a persistent connection. If you don’t need one (such as a website that is mostly HTML files or PHP files that don’t call the db) then you don’t need to use it. mysql_connect establishes a connection for the duration of the script that access the db. Once the script has finished executing it closes the connection. The only time you need to close the connection manually is if you jump out of the script for any reason.
    If you do use mysql_pconnect. You only need to call it once for the session. That’s the beauty of it. It will hold open a connection to the db that you can use over and over again simply by calling the resource ID whenever you need to interact with the db.
    8. What is the difference between echo and print statement?
    There is a slight difference between print and echo which would depend on how you want to use the outcome. Using the print method can return a true/false value. This may be helpful during a script execution of somesort. Echo does not return a value, but has been considered as a faster executed command. All this can get into a rather complicated discussion, so for now, you can just use whichever one you prefer.
    9. How to make a download page in own site, which i can know that how many file has been loaded by particular user or particular ip address?
    We can use hyperlink having URL where file are kept. and we only allow regisetered user to download. from session of user we can get the user detail
    10) What is the difference between inner join and outer join?

    Inner join displays rows from table where the data is available in both the tables, where in outer join we can configure it to bring out rows from one table where the data is missing in other table for the corresponding rows.
    Inner join
    Say you have one table of CUSTOMERS and one table of ORDERS. Each row in the ORDERS table has a reference (foreign key reference) to a customer id which represents what customer placed that order. If you want to run a query that lists the orders along with the names of the customers who ordered them (since a customer id number itself it pretty useless), you will want to execute a join query:
    SELECT CUSTOMERS.NAME, ORDERS.NAME
    FROM CUSTOMERS
    INNER JOIN ORDERS
    ON CUSTOMERS.ID = ORDERS.CUSTOMER_ID
    Outer join
    If for some reason, you wanted the query results to return all customer name regardless of whether they placed an order, you can use one of two types of OUTER JOINS, in this case, a LEFT JOIN:
    SELECT CUSTOMERS.NAME, ORDERS.NAME
    FROM CUSTOMERS
    LEFT JOIN ORDERS
    ON CUSTOMERS.ID = ORDERS.CUSTOMER_ID

    Categories
    MySQL PHP

    PHP interview questions & ANSWERS

    Q:1 What are the differences between Get and post methods in form submitting.
    give the case where we can use get and we can use post methods?
    A:1
    When to use GET or  POST

    The HTML 2.0 specification says, in section Form
    Submission (and the HTML 4.0 specification repeats this with minor
    stylistic changes):

    –>If the processing of a form is idempotent
    (i.e. it has no lasting observable effect on the state of the
    world), then the form method should be GET. Many database searches
    have no visible side-effects and make ideal applications of query
    forms.

    –>If the service associated with the processing of a form has side
    effects (for example, modification of a database or subscription to
    a service), the method should be POST.
    How the form data is transmitted?

    quotation from the HTML 4.0 specification

    –> If the method is “get” – -, the user agent
    takes the value of action, appends a ? to it, then appends the form
    data set, encoded using the application/x-www-form-urlencoded
    content type. The user agent then traverses the link to this URI. In
    this scenario, form data are restricted to ASCII codes.
    –> If the method is “post” –, the user agent conducts an HTTP post
    transaction using the value of the action attribute and a message
    created according to the content type specified by the enctype
    attribute.
    Quote from CGI FAQ

    Firstly, the the HTTP protocol specifies
    differing usages for the two methods. GET requests should always be
    idempotent on the server. This means that whereas one GET request
    might (rarely) change some state on the Server, two or more
    identical requests will have no further effect.

    This is a theoretical point which is also good
    advice in practice. If a user hits “reload” on his/her browser, an
    identical request will be sent to the server, potentially resulting
    in two identical database or
    guestbook entries, counter increments, etc. Browsers may reload a
    GET URL automatically, particularly if cacheing is disabled (as is
    usually the case with CGI output), but will typically prompt the
    user before
    re-submitting a POST request. This means you’re far less likely to
    get inadvertently-repeated entries from POST.

    GET is (in theory) the preferred method for
    idempotent operations, such as querying a database, though it
    matters little if you’re using a form. There is a further practical
    constraint that many systems have built-in limits to the length of a
    GET request they can handle: when the total size of a request (URL+params)
    approaches or exceeds 1Kb, you are well-advised to use POST in any
    case.

    I would prefer POST when I don’t want the status to
    be change when user resubmits. And GET
    when it does not matter.

    Q:2 Who is the father of PHP and explain the changes in PHP versions?
    A:2 Rasmus Lerdorf is known as the father of PHP.PHP/FI 2.0 is an early and no longer supported version of PHP. PHP 3
    is the successor to PHP/FI 2.0 and is a lot nicer. PHP 4 is the current
    generation of PHP, which uses the
    Zend engine
    under the
    hood. PHP 5 uses
    Zend engine 2 which,
    among other things, offers many additionalOOP features

    Q:3 How can we submit a form without a submit button?
    A:3 The main idea behind this is to use Java script submit() function in
    order to submit the form without explicitly clicking any submit button.
    You can attach the document.formname.submit() method to onclick,
    onchange events of different inputs and perform the form submission. you
    can even built a timer function where you can automatically submit the
    form after xx seconds once the loading is done (can be seen in online
    test sites).

    Q:4 In how many ways we can retrieve the data in the result set of
    MySQL using PHP?

    A:4 You can do it by 4 Ways1. mysql_fetch_row.
    2. mysql_fetch_array
    3. mysql_fetch_object
    4. mysql_fetch_assoc

    Q:5 What is the difference between mysql_fetch_object and
    mysql_fetch_array?

    A:5 mysql_fetch_object() is similar tomysql_fetch_array(), with one difference –
    an object is returned, instead of an array. Indirectly, that means that
    you can only access the data by the field names, and not by their
    offsets (numbers are illegal property names).

    Q:6 What is the difference between $message and $$message?
    A:6 It is a classic example of PHP’s variable variables. take the
    following example.$message = “Mizan”;$$message = “is a moderator of PHPXperts.”;$message is a simple PHP variable that we are used to. But the
    $$message is not a very familiar face. It creates a variable name $mizan
    with the value “is a moderator of PHPXperts.” assigned. break it like
    this${$message} => $mizanSometimes it is convenient to be able to have variable variable
    names. That is, a variable name which can be set and used dynamically.

    Q:7 How can we extract string ‘abc.com ‘ from a string ‘http://info@abc.com’
    using regular expression of PHP?

    A:7 preg_match(”/^http:\/\/.+@(.+)$/”,’http://info@abc.com’,$found);
    echo $found[1];

    Q:8 How can we create a database using PHP and MySQL?
    A:8 We can create MySQL database with the use of
    mysql_create_db(“Database Name”)

    Q:9 What are the differences between require and include,
    include_once and require_once?
    A:9

    The include() statement includes
    and evaluates the specified file.The documentation below also applies to
    require(). The two constructs
    are identical in every way except how they handle
    failure. include() produces a
    Warning while require() results
    in a Fatal Error. In other words, use
    require() if you want a missing
    file to halt processing of the page.
    include() does not behave this way, the script will
    continue regardless.

    The include_once()
    statement includes and evaluates the
    specified file during the execution of
    the script. This is a behavior similar
    to the include()
    statement, with the only difference
    being that if the code from a file has
    already been included, it will not be
    included again. As the name suggests, it
    will be included just once.include_once()
    should be used in cases where the same
    file might be included and evaluated
    more than once during a particular
    execution of a script, and you want to
    be sure that it is included exactly once
    to avoid problems with function
    redefinitions, variable value
    reassignments, etc.

    require_once()
    should be used in cases where the same
    file might be included and evaluated
    more than once during a particular
    execution of a script, and you want to
    be sure that it is included exactly once
    to avoid problems with function
    redefinitions, variable value
    reassignments, etc.

    Q:10 Can we use include (”abc.PHP”) two times in a PHP page “makeit.PHP”?
    A:10 Yes we can use include() more than one time in any page though it is
    not a very good practice.

    Q:11 What are the different tables present in MySQL, which type of
    table is generated when we are creating a table in the following syntax:
    create table employee (eno int(2),ename varchar(10)) ?

    A:11 Total 5 types of tables we can create
    1. MyISAM
    2. Heap
    3. Merge
    4. INNO DB
    5. ISAM
    MyISAM is the default storage engine as of MySQL 3.23 and as a result if
    we do not specify the table name explicitly it will be assigned to the
    default engine.

    Q:12 Functions in IMAP, POP3 AND LDAP?
    A:12 These functions enable you to operate with the IMAP protocol, as well as the NNTPPOP3 and local mailbox access methods  You can find these specific information in PHP Manual.

    Q:13 How can I execute a PHP script using command line?
    A:13 As of version 4.3.0, PHP supports a new SAPI type (Server
    Application Programming Interface) named CLI which means Command Line
    Interface. Just run the PHP CLI (Command Line Interface) program and
    provide the PHP script file name as the command line argument. For
    example, “php myScript.php”, assuming “php” is the command to invoke the
    CLI program.
    Be aware that if your PHP script was written for the Web CGI interface,
    it may not execute properly in command line environment.

    Q:14 Suppose your Zend engine supports the mode Then how can u
    configure your PHP Zend engine to support mode ?

    A:14 In php.ini file:
    set
    short_open_tag=on
    to make PHP support

    Q:15 Shopping cart online validation i.e. how can we configure Paypal,
    etc.?

    A:15 We can find the detail documentation about different paypal
    integration process at the following site

    PayPal PHP
    SDK : http://www.paypaldev.org

    Q:16 What is meant by nl2br()?
    A:16 Inserts HTML line breaks (
    ) before all newlines in a string
    string nl2br (string); Returns string with ” inserted before all
    newlines. For example: echo nl2br(”god bless\n you”) will output “god
    bless
    you” to your browser.

    Q:17 Draw the architecture of Zend engine?
    A:17 The Zend Engine is the internal compiler and runtime engine used by
    PHP4. Developed by Zeev Suraski and Andi Gutmans, the Zend Engine is an
    abbreviation of their names. In the early days of PHP4, it worked as
    follows:
    The PHP script was loaded by the Zend Engine and compiled into Zend
    opcode. Opcodes, short for operation codes, are low level binary
    instructions. Then the opcode was executed and the HTML generated sent
    to the client. The opcode was flushed from memory after execution.Today, there are a multitude of products and techniques to help you
    speed up this process. In the following diagram, we show the how modern
    PHP scripts work; all the shaded boxes are optional.
    PHP Scripts are loaded into memory and compiled into Zend opcodes.

    Q:18 What are the current versions of apache, PHP, and MySQL?
    A:18 As of February, 2007 the current versions arePHP: php5.2.1
    MySQL: MySQL 5.2
    Apache: Apache 2.2.4Note: visit www.php.net,

    http://dev.mysql.com/downloads/mysql/,
    www.apache.org to get current
    versions.

    Q:19 What are the reasons for selecting lamp (Linux, apache, MySQL,
    PHP) instead of combination of other software programs, servers and
    operating systems?

    A:19 All of those are open source resource. Security of Linux is very
    very more than windows. Apache is a better server that IIS both in
    functionality and security. MySQL is world most popular open source
    database. PHP is more faster that asp or any other scripting language.

    Q:20 How can we encrypt and decrypt a data present in a MySQL table
    using MySQL?

    A:20 AES_ENCRYPT () and AES_DECRYPT ()

    Q:21 How can we encrypt the username and password using PHP?
    A:21 The functions in this section perform encryption and decryption, and
    compression and uncompression:

    encryption decryption
    AES_ENCRYT() AES_DECRYPT()
    ENCODE() DECODE()
    DES_ENCRYPT() DES_DECRYPT()
    ENCRYPT() Not available
    MD5() Not available
    OLD_PASSWORD() Not available
    PASSWORD() Not available
    SHA() or SHA1() Not available
    Not available UNCOMPRESSED_LENGTH()

    Q:22 What are the features and advantages of object-oriented
    programming?

    A:22 One of the main advantages of OO programming is its ease of
    modification; objects can easily be modified and added to a system there
    by reducing maintenance costs. OO programming is also considered to be
    better at modeling the real world than is procedural programming. It
    allows for more complicated and flexible interactions. OO systems are
    also easier for non-technical personnel to understand and easier for
    them to participate in the maintenance and enhancement of a system
    because it appeals to natural human cognition patterns.
    For some systems, an OO approach can speed development time since many
    objects are standard across systems and can be reused. Components that
    manage dates, shipping, shopping carts, etc. can be purchased and easily
    modified for a specific system

    Q:23 What are the differences between procedure-oriented languages and
    object-oriented languages?

    A:23 Traditional programming has the following characteristics:Functions are written sequentially, so that a change in programming can
    affect any code that follows it.
    If a function is used multiple times in a system (i.e., a piece of code
    that manages the date), it is often simply cut and pasted into each
    program (i.e., a change log, order function, fulfillment system, etc).
    If a date change is needed (i.e., Y2K when the code needed to be changed
    to handle four numerical digits instead of two), all these pieces of
    code must be found, modified, and tested.
    Code (sequences of computer instructions) and data (information on which
    the instructions operates on) are kept separate. Multiple sets of code
    can access and modify one set of data. One set of code may rely on data
    in multiple places. Multiple sets of code and data are required to work
    together. Changes made to any of the code sets and data sets can cause
    problems through out the system.Object-Oriented programming takes a radically different approach:Code and data are merged into one indivisible item – an object (the
    term “component” has also been used to describe an object.) An object is
    an abstraction of a set of real-world things (for example, an object may
    be created around “date”) The object would contain all information and
    functionality for that thing (A date
    object it may contain labels like January, February, Tuesday, Wednesday.
    It may contain functionality that manages leap years, determines if it
    is a business day or a holiday, etc., See Fig. 1). Ideally, information
    about a particular thing should reside in only one place in a system.
    The information within an object is encapsulated (or hidden) from the
    rest of the system.
    A system is composed of multiple objects (i.e., date function, reports,
    order processing, etc., See Fig 2). When one object needs information
    from another object, a request is sent asking for specific information.
    (for example, a report object may need to know what today’s date is and
    will send a request to the date object) These requests are called
    messages and each object has an interface that manages messages.
    OO programming languages include features such as “class”, “instance”,
    “inheritance”, and “polymorphism” that increase the power and
    flexibility of an object.

    Q:24 What is the use of friend function?
    A:24 Sometimes a function is best shared among a number of different
    classes. Such functions can be declared either as member functions of
    one class or as global functions. In either case they can be set to be
    friends of other classes, by using a friend specifier in the class that
    is admitting them. Such functions can use all attributes of the class
    which names them as a friend, as if they were themselves members of that
    class.
    A friend declaration is essentially a prototype for a member function,
    but instead of requiring an implementation with the name of that class
    attached by the double colon syntax, a global function or member
    function of another class provides the match.

    Q:25 What are the differences between public, private, protected,
    static, transient, final and volatile?

    A:25 Public: Public declared items can be accessed everywhere.
    Protected: Protected limits access to inherited and parent
    classes (and to the class that defines the item).
    Private: Private limits visibility only to the class that defines
    the item.
    Static: A static variable exists only in a local function scope,
    but it does not lose its value when program execution leaves this scope.
    Final: Final keyword prevents child classes from overriding a
    method by prefixing the definition with final. If the class itself is
    being defined final then it cannot be extended.
    transient: A transient variable is a variable that may not
    be serialized.
    volatile: a variable that might be concurrently modified by multiple
    threads should be declared volatile. Variables declared to be volatile
    will not be optimized by the compiler because their value can change at
    any time.

    Q:26 What are the different types of errors in PHP?
    A:26 Three are three types of errors:1. Notices: These are trivial,
    non-critical errors that PHP encounters while executing a script – for
    example, accessing a variable that has not yet been defined. By default,
    such errors are not displayed to the user at all – although, as you will
    see, you can change this default behavior.2. Warnings: These are more serious errors – for example, attempting
    to include() a file which does not exist. By default, these errors are
    displayed to the user, but they do not result in script termination.3. Fatal errors: These are critical errors – for example,
    instantiating an object of a non-existent class, or calling a
    non-existent function. These errors cause the immediate termination of
    the script, and PHP’s default behavior is to display them to the user
    when they take place.

    Q:27 What is the functionality of the function strstr and stristr?
    A:27 strstr:

    Returns part of haystack
    string from the first occurrence of
    needle to the end of
    haystack.If needle is not found,
    returns FALSE.

    If needle is not a
    string, it is converted to an integer and applied as the
    ordinal value of a character.

    This function is case-sensitive. For
    case-insensitive searches, use
    stristr().

    Q:28 What are the differences between PHP 3 and PHP 4 and PHP 5?
    A:28 Please read the release notes at
    http://www.php.net.

    Q:29 How can we convert asp pages to PHP pages?
    A:29 there are lots of tools available for asp to PHP conversion. you can
    search Google for that. the best one is available athttp://asp2php.naken.cc./

    Q:30 What is the functionality of the function htmlentities?
    A:30 Convert all applicable characters to HTML entities
    This function is identical to htmlspecialchars() in all ways, except
    with htmlentities(), all characters which have HTML character entity
    equivalents are translated into these entities.

    Q:31 How can we get second of the current time using date function?
    A:31 $second = date(”s”);

    Q:32 How can we convert the time zones using PHP?
    A:32 By using date_default_timezone_get and
    date_default_timezone_set function on PHP 5.1.0

    // Discover what 8am in Tokyo relates to on the East Coast of the US

    // Set the default timezone to Tokyo time:
    date_default_timezone_set(‘Asia/Tokyo’);

    // Now generate the timestamp for that particular timezone, on Jan 1st, 2000
    $stamp = mktime(8, 0, 0, 1, 1, 2000);

    // Now set the timezone back to US/Eastern
    date_default_timezone_set(‘US/Eastern’);

    // Output the date in a standard format (RFC1123), this will print:
    // Fri, 31 Dec 1999 18:00:00 EST
    echo ‘

    ‘, date(DATE_RFC1123, $stamp) ,’

    ‘;?>

    Q:33 What is meant by urlencode and urldecode?
    A:33 URLencode returns a string in which all non-alphanumeric characters
    except -_. have been replaced with a percent (%)
    sign followed by two hex digits and spaces encoded as plus (+)
    signs. It is encoded the same way that the posted data from a WWW form
    is encoded, that is the same way as in
    application/x-www-form-urlencoded media type.

    urldecode decodes any %##
    encoding in the given string.

    Q:34 What is the difference between the functions unlink and unset?
    A:34 unlink() deletes the given file from the file system.
    unset() makes a variable undefined.

    Q:35 How can we register the variables into a session?
    A:35 $_SESSION[’name’] = “Mizan”;

    Q:36 How can we get the properties (size, type, width, height) of an
    image using PHP image functions?

    A:36 To know the Image type use exif_imagetype () function
    To know the Image size use getimagesize () function
    To know the image width use imagesx () function
    To know the image height use imagesy() function t

    Q:37 How can we get the browser properties using PHP?
    A:37 By using
    $_SERVER[‘HTTP_USER_AGENT’]
    variable.

    Q:38 What is the maximum size of a file that can be uploaded using PHP
    and how can we change this?

    A:38 By default the maximum size is 2MB. and we can change the following
    setup at php.iniupload_max_filesize = 2M

    Q:39 How can we increase the execution time of a PHP script?
    A:39 by changing the following setup at php.inimax_execution_time = 30
    ; Maximum execution time of each script, in seconds

    Q:40 How can we take a backup of a MySQL table and how can we restore
    it. ?

    A:40 To backup: BACKUP TABLE tbl_name[,tbl_name…] TO
    ‘/path/to/backup/directory’
    RESTORE TABLE tbl_name[,tbl_name…] FROM ‘/path/to/backup/directory’mysqldump: Dumping Table Structure and DataUtility to dump a database or a collection of database for backup or
    for transferring the data to another SQL server (not necessarily a MySQL
    server). The dump will contain SQL statements to create the table and/or
    populate the table.
    -t, –no-create-info
    Don’t write table creation information (the CREATE TABLE statement).
    -d, –no-data
    Don’t write any row information for the table. This is very useful if
    you just want to get a dump of the structure for a table!

    Q:41 How can we optimize or increase the speed of a MySQL select
    query?

    A:41

    * first of all instead of using select * from table1, use select
    column1, column2, column3.. from table1
    * Look for the opportunity to introduce index in the table you are
    querying.
    * use limit keyword if you are looking for any specific number of
    rows from the result set.

    Q:42 How many ways can we get the value of current session id?
    A:42 session_id() returns the session id for the current session.

    Q:43 How can we destroy the session, how can we unset the variable of
    a session?

    A:43 session_unregister — Unregister a global variable from the current
    session
    session_unset — Free all session variables

    Q:44 How can we destroy the cookie?
    A:44 Set the cookie in past.

    Q:45 How many ways we can pass the variable through the navigation
    between the pages?

    A:45

    * GET/QueryString
    * POST

    Q:46 What is the difference between ereg_replace() and eregi_replace()?
    A:46 eregi_replace() function is identical to ereg_replace() except that
    this ignores case distinction when matching alphabetic
    characters.eregi_replace() function is identical to ereg_replace()
    except that this ignores case distinction when matching alphabetic
    characters.

    Q:47 What are the different functions in sorting an array?
    A:47 Sort(), arsort(),
    asort(), ksort(),
    natsort(), natcasesort(),
    rsort(), usort(),
    array_multisort(), and
    uksort().

    Q:48 How can we know the count/number of elements of an array?
    A:48 2 ways
    a) sizeof($urarray) This function is an alias of count()
    b) count($urarray)

    Q:49 What is the PHP predefined variable that tells the What types of
    images that PHP supports?

    A:49 Though i am not sure if this is wrong or not, With the exif
    extension you are able to work with image meta data.

    Q:50 How can I know that a variable is a number or not using a
    JavaScript?

    A:50 bool is_numeric ( mixed var)
    Returns TRUE if var is a number or a numeric string, FALSE otherwise.or use isNaN(mixed var)The isNaN() function is used to check if a value is not a number.

    Q:51 List out some tools through which we can draw E-R diagrams for
    mysql.

    A:51 Case Studio
    Smart Draw

    Q:52 How can I retrieve values from one database server and store them
    in other database server using PHP?

    A:52 we can always fetch from one database and rewrite to another. here
    is a nice solution of it.$db1 = mysql_connect(”host”,”user”,”pwd”)
    mysql_select_db(”db1″, $db1);
    $res1 = mysql_query(”query”,$db1);$db2 = mysql_connect(”host”,”user”,”pwd”)
    mysql_select_db(”db2″, $db2);
    $res2 = mysql_query(”query”,$db2);At this point you can only fetch records from you previous ResultSet,
    i.e $res1 – But you cannot execute new query in $db1, even if you
    supply the link as because the link was overwritten by the new db.so at this point the following script will fail
    $res3 = mysql_query(”query”,$db1); //this will failSo how to solve that?

    take a look below.
    $db1 = mysql_connect(”host”,”user”,”pwd”)
    mysql_select_db(”db1″, $db1);
    $res1 = mysql_query(”query”,$db1);

    $db2 = mysql_connect(”host”,”user”,”pwd”, true)
    mysql_select_db(”db2″, $db2);
    $res2 = mysql_query(”query”,$db2);

    So mysql_connect has another optional boolean parameter which
    indicates whether a link will be created or not. as we connect to the
    $db2 with this optional parameter set to ‘true’, so both link will
    remain live.

    now the following query will execute successfully.
    $res3 = mysql_query(”query”,$db1);

    Thanks goes to Hasan and Hasin for this solution.

    Q:53 List out the predefined classes in PHP?
    A:53 Directory
    stdClass
    __PHP_Incomplete_Class
    exception
    php_user_filter

    Q:54 How can I make a script that can be bi-language (supports
    English, German)?

    A:54 You can maintain two separate language file for each of the
    language. all the labels are putted in both language files as variables
    and assign those variables in the PHP source. on runtime choose the
    required language option.

    Q:55 What are the difference between abstract class and interface?
    A:55 Abstract class: abstract classes are the class where one or more
    methods are abstract but not necessarily all method has to be abstract.
    Abstract methods are the methods, which are declare in its class but not
    define. The definition of those methods must be in its extending class.Interface: Interfaces are one type of class where all the methods are
    abstract. That means all the methods only declared but not defined. All
    the methods must be define by its implemented class.

    Q:56 How can we send mail using JavaScript?
    A:56 JavaScript does not have any networking capabilities as it is
    designed to work on client site. As a result we can not send mails using
    JavaScript. But we can call the client side mail protocol mailto
    via JavaScript to prompt for an email to send. this requires the client
    to approve it.

    Q:57 How can we repair a MySQL table?
    A:57 The syntex for repairing a MySQL table is
    REPAIR TABLENAME, [TABLENAME, ], [Quick],[Extended]
    This command will repair the table specified if the quick is given the
    MySQL will do a repair of only the index tree if the extended is given
    it will create index row by row

    Q:58 What are the advantages of stored procedures, triggers, indexes?
    A:58 A stored procedure is a set of SQL commands that can be compiled and
    stored in the server. Once this has been done, clients don’t need to
    keep re-issuing the entire query but can refer to the stored procedure.
    This provides better overall performance because the query has to be
    parsed only once, and less information needs to be sent between the
    server and the client. You can also raise the conceptual level by having
    libraries of functions in the server. However, stored procedures of
    course do increase the load on the database server system, as more of
    the work is done on the server side and less on the client (application)
    side.Triggers will also be implemented. A trigger is effectively a type of
    stored procedure, one that is invoked when a particular event occurs.
    For example, you can install a stored procedure that is triggered each
    time a record is deleted from a transaction table and that stored
    procedure automatically deletes the corresponding customer from a
    customer table when all his transactions are deleted.Indexes are used to find rows with specific column values quickly.
    Without an index, MySQL must begin with the first row and then read
    through the entire table to find the relevant rows. The larger the
    table, the more this costs. If the table has an index for the columns in
    question, MySQL can quickly determine the position to seek to in the
    middle of the data file without having to look at all the data. If a
    table has 1,000 rows, this is at least 100 times faster than reading
    sequentially. If you need to access most of the rows, it is faster to
    read sequentially, because this minimizes disk seeks.

    Q:59 What is the maximum length of a table name, database name, and
    fieldname in MySQL?

    A:59 The following table describes the maximum length for each type of
    identifier.

    Identifier Maximum Length
    (bytes)
    Database 64
    Table 64
    Column 64
    Index 64
    Alias 255

    There are some restrictions on the characters that may appear in
    identifiers:

    Q:60 How many values can the SET function of MySQL take?
    A:60 MySQL set can take zero or more values but at the maximum it can
    take 64 values

    Q:61 What are the other commands to know the structure of table using
    MySQL commands except explain command?

    A:61 describe Table-Name;

    Q:62 How many tables will create when we create table, what are they?
    A:62 The ‘.frm’ file stores the table definition.
    The data file has a ‘.MYD’ (MYData) extension.
    The index file has a ‘.MYI’ (MYIndex) extension,

    Q:63 What is the purpose of the following files having extensions 1) .frm
    2) .myd 3) .myi? What do these files contain?

    A:63 In MySql, the default table type is MyISAM.
    Each MyISAM table is stored on disk in three files. The files have names
    that begin with the table name and have an extension to indicate the
    file type.
    The ‘.frm’ file stores the table definition.
    The data file has a ‘.MYD’ (MYData) extension.
    The index file has a ‘.MYI’ (MYIndex) extension,

    Q:64 What is maximum size of a database in MySQL?
    A:64 If the operating system or filesystem places a limit on the number
    of files in a directory, MySQL is bound by that constraint.The efficiency of the operating system in handling large numbers of
    files in a directory can place a practical limit on the number of tables
    in a database. If the time required to open a file in the directory
    increases significantly as the number of files increases, database
    performance can be adversely affected.
    The amount of available disk space limits the number of tables.
    MySQL 3.22 had a 4GB (4 gigabyte) limit on table size. With the MyISAM
    storage engine in MySQL 3.23, the maximum table size was increased to
    65536 terabytes (2567 – 1 bytes). With this larger allowed table size,
    the maximum effective table size for MySQL databases is usually
    determined by operating system constraints on file sizes, not by MySQL
    internal limits.The InnoDB storage engine maintains InnoDB tables within a tablespace
    that can be created from several files. This allows a table to exceed
    the maximum individual file size. The tablespace can include raw disk
    partitions, which allows extremely large tables. The maximum tablespace
    size is 64TB.
    The following table lists some examples of operating system file-size
    limits. This is only a rough guide and is not intended to be definitive.
    For the most up-to-date information, be sure to check the documentation
    specific to your operating system.
    Operating System File-size LimitLinux 2.2-Intel 32-bit 2GB (LFS: 4GB)
    Linux 2.4+ (using ext3 filesystem) 4TB
    Solaris 9/10 16TB
    NetWare w/NSS filesystem 8TB
    Win32 w/ FAT/FAT32 2GB/4GB
    Win32 w/ NTFS 2TB (possibly larger)
    MacOS X w/ HFS+ 2TB

    Q:65 Give the syntax of Grant and Revoke commands?
    A:65 The generic syntax for grant is as following
    > GRANT [rights] on [database/s] TO [username@hostname] IDENTIFIED BY
    [password]
    now rights can be
    a) All privileges
    b) combination of create, drop, select, insert, update and delete etc.We can grant rights on all databse by using *.* or some specific
    database by database.* or a specific table by database.table_name
    username@hotsname can be either username@localhost, username@hostname
    and username@%
    where hostname is any valid hostname and % represents any name, the *.*
    any condition
    password is simply the password of userThe generic syntax for revoke is as following
    > REVOKE [rights] on [database/s] FROM [username@hostname]
    now rights can be as explained above
    a) All privileges
    b) combination of create, drop, select, insert, update and delete etc.
    username@hotsname can be either username@localhost, username@hostname
    and username@%
    where hostname is any valid hostname and % represents any name, the *.*
    any condition

    Q:66 Explain Normalization concept?
    A:66 The normalization process involves getting our data to conform to
    three progressive normal forms, and a higher level of normalization
    cannot be achieved until the previous levels have been achieved (there
    are actually five normal forms, but the last two are mainly academic and
    will not be discussed).First Normal FormThe First Normal Form (or 1NF) involves removal of redundant data
    from horizontal rows. We want to ensure that there is no duplication of
    data in a given row, and that every column stores the least amount of
    information possible (making the field atomic).Second Normal FormWhere the First Normal Form deals with redundancy of data across a
    horizontal row, Second Normal Form (or 2NF) deals with redundancy of
    data in vertical columns. As stated earlier, the normal forms are
    progressive, so to achieve Second Normal Form, your tables must already
    be in First Normal Form.Third Normal Form

    I have a confession to make; I do not often use Third Normal Form. In
    Third Normal Form we are looking for data in our tables that is not
    fully dependant on the primary key, but dependant on another value in
    the table

    Q:67 How can we find the number of rows in a table using MySQL?
    A:67 Use this for mysql
    >SELECT COUNT(*) FROM table_name;

    Q:68 How can we find the number of rows in a result set using PHP?
    A:68 $result = mysql_query($sql, $db_link);
    $num_rows = mysql_num_rows($result);
    echo “$num_rows rows found”;

    Q:69 How many ways we can we find the current date using MySQL?
    A:69 SELECT CURDATE();
    CURRENT_DATE() = CURDATE()
    for time use
    SELECT CURTIME();
    CURRENT_TIME() = CURTIME()

    Q:70 What are the advantages and disadvantages of Cascading Style
    Sheets?

    A:70 External Style SheetsAdvantagesCan control styles for multiple documents at once. Classes can be
    created for use on multiple HTML element types in many documents.
    Selector and grouping methods can be used to apply styles under complex
    contextsDisadvantagesAn extra download is required to import style information for each
    document The rendering of the document may be delayed until the external
    style sheet is loaded Becomes slightly unwieldy for small quantities of
    style definitionsEmbedded Style Sheets

    Advantages

    Classes can be created for use on multiple tag types in the document.
    Selector and grouping methods can be used to apply styles under complex
    contexts. No additional downloads necessary to receive style information

    Disadvantages

    This method can not control styles for multiple documents at once

    Inline Styles

    Advantages

    Useful for small quantities of style definitions. Can override other
    style specification methods at the local level so only exceptions need
    to be listed in conjunction with other style methods

    Disadvantages

    Does not distance style information from content (a main goal of
    SGML/HTML). Can not control styles for multiple documents at once.
    Author can not create or control classes of elements to control multiple
    element types within the document. Selector grouping methods can not be
    used to create complex element addressing scenarios

    Q:71 What type of inheritance that PHP supports?
    A:71 In PHP an extended class is always dependent on a single base class,
    that is, multiple inheritance is not supported. Classes are extended
    using the keyword ‘extends’.

    Q:72 What is the difference between Primary Key and
    Unique key?

    A:72 Primary Key: A column in a table whose values uniquely identify the
    rows in the table. A primary key value cannot be NULL.

    Unique Key: Unique Keys are used to uniquely identify each row in the
    table. There can be one and only one row for each unique key value. So
    NULL can be a unique key.There can be only one primary key for a table but there can be more
    than one unique for a table.

    Q:73 The structure of table view buyers is as follows:

    Field Type Null Key Default Extra
    user_pri_id int(15) PRI null auto_increment
    userid varchar(10) YES null

    the value of user_pri_id the last row 999 then What will happen in
    the following conditions?

    Condition1: Delete all the rows and insert another row then.
    What is the starting value for this auto incremented field user_pri_id ,
    Condition2: Delete the last row(having the field value 999) and
    insert another row then. What is the value for this auto incremented
    field user_pri_id
    A:73 In both cases let the value for auto increment field be n then next
    row will have value n+1 i.e. 1000

    Q:74 What are the advantages/disadvantages of MySQL and PHP?
    A:74 Both of them are open source software (so free of cost), support
    cross platform. php is faster then ASP and JSP.

    Q:75 What is the difference between GROUP BY and ORDER BY in Sql?
    A:75 ORDER BY [col1],[col2],…,[coln]; Tels DBMS according to what columns
    it should sort the result. If two rows will hawe the same value in col1
    it will try to sort them according to col2 and so on.GROUP BY
    [col1],[col2],…,[coln]; Tels DBMS to group results with same value of
    column col1. You can use COUNT(col1), SUM(col1), AVG(col1) with it, if
    you want to count all items in group, sum all values or view average

    Q:76 What is the difference between char and varchar data types?
    A:76 Set char to occupy n bytes and it will take n bytes even if u r
    storing a value of n-m bytes
    Set varchar to occupy n bytes and it will take only the required space
    and will not use the n bytes
    eg. name char(15) will waste 10 bytes if we store ‘mizan’, if each char
    takes a byte
    eg. name varchar(15) will just use 5 bytes if we store ‘mizan’, if each
    char takes a byte. rest 10 bytes will be free.

    Q:77 What is the functionality of md5 function in PHP?
    A:77 Calculate the md5 hash of a string. The hash is a 32-character
    hexadecimal number. I use it to generate keys which I use to identify
    users etc. If I add random no techniques to it the md5 generated now
    will be totally different for the same string I am using.

    Q:78 How can I load data from a text file into a table?
    A:78 you can use LOAD DATA INFILE file_name; syntax to load data
    from a text file. but you have to make sure thata) data is delimited
    b) columns and data matched correctly

    Q:79 How can we know the number of days between two given dates using
    MySQL?

    A:79 SELECT DATEDIFF(’2007-03-07′,’2005-01-01′);

    Q:80 How can we know the number of days between two given dates using
    PHP?

    A:80 $date1 = date(’Y-m-d’);
    $date2 = ‘2006-08-15′;
    $days = (strtotime($date1) – strtotime($date2)) / (60 * 60 * 24);

     

    Q:81 What is ‘float’ property in CSS?

    A:81 The float property sets where an image or a text will appear in another element.

        

    Q:82 What is descendant structure in CSS?

    A:82 Descendant selectors are used to select elements that are descendants of another element in the document tree.For example, you may wish to target a specific <em> element on the page, but not all <em> elements. A sample document could contain the following code: <body>

    <h1>Heading <em>here</em> </h1>

    <p>Lorem ipsum dolor <em>sit</em> amet.</p>

    </body> The document tree diagram (with the <em> element to be targeted) would be:Document tree showing descendant selectorsIf you use a type selector like the example below, you will select all <em> elements on the page:

     

    em {color: blue; } However, if you use a descendant selector, you can refine the <em> elements that you select. The rule below will only select <em> elements that are descendants of <p> elements. If this rule is applied, the <em> element within the <h1> will not be colored blue.

     

    p em {color: blue; } You can also jump levels in the document tree structure to select descendants. For example, the following code:

     

    <body>

    <p>Lorem ipsum dolor <em>sit</em> amet.</p>

    <ul>

    <li>item 1</li>

    <li>item 2</li>

    <li><em>item 3</em></li>

    </ul>

    </body> The document tree (with a third-level <em> element highlighted) would be:

     

    Document tree showing descendant selectors

     

    Using the following rule you can isolate any <em> element inside a <ul> element, without having to describe the <li> element. If this rule is applied, any <em> element within a <ul> element will be colored blue. However, the <em> element within the <p> will not be colored blue:

     

    ul em {color: blue; } Descendant selectors are well supported across standards-compliant browsers.

        

    Q:83 What is Child Descendant structure in CSS?

    A:83

    Child selectors

     

    A child selector is used to select an element that is a direct child of another element (parent). Child selectors will not select all descendants, only direct children.

     

    For example, you may wish to target an <em> that is a direct child of a <div>, but not other <em> elements that are descendants of the <div>. A sample document could contain the following code:

     

    <body>

    <h1>Heading <em>text</em></h1>

    <div>

    This is some <em>text</em>

    <p>This is a paragraph of <em>text</em></p>

    </div>

    </body>

    The document tree (highlighting the <em> that is a child of the <div>) would be:

     

    Document tree showing child selector

     

    Using the following rule you can target any <em> element that is a child of the <div>. Other <em> elements that are descendants but not direct children of the <div> will not be targeted.

     

    div > em { color: blue; }

     

    OR

     

    div>em { color: blue; }

    Child selectors are not supported by Windows Internet Explorer 5, 5.5 and 6, but are supported by most other standards-compliant browsers.

        

    Q:84 How to create a class in JavaScript?

    A:84 Classes can seem off-putting at first, but once you see the point of them, their use can be invaluable.We have already met objects. A computer object is a representation of a real object. For an estate agent the object may be a house, including information about the number of rooms and the price.An estate agent may have a lot of houses available. These houses all have different characteristics, and as objects they all go through the same processes. They are viewed, surveyed and bought, and so on.A full estate agent program would be difficult to demonstrate here, but we can introduce the use of classes.In this example, we have the house class. The house class produces house objects, all with object properties, such as number of rooms and price, and all having access to the same methods, such as sold and bought.

     

    So a class can create objects with a group of properties and methods.

     

    JavaScript doesn’t have a keyword specific to class, so we must go back to basics and develop classes in a different way. This isn’t very difficult.

    Class Properties

     

    Let us examine a very small estate agent program.

     

    <HTML>

    <HEAD>

    <TITLE>Estate Agent</TITLE>

    <SCRIPT>

    function House(rooms,price,garage) {

    this.rooms=rooms;

    this.price=price;

    this.garage=garage;

    }

    house1=new House(4,100000,false);

    house2=new House(5,200000,true);

    with (house1) document.write(’House 1 has ‘+rooms+’ rooms, ‘+(garage?’a’:’no’)+’ garage, and costs £’+price+’<BR>’);

    with (house2) document.write(’House 2 has ‘+rooms+’ rooms, ‘+(garage?’a’:’no’)+’ garage, and costs £’+price+’<BR>’);

    </SCRIPT>

    </HEAD>

    </HTML>

     

    We define a House function that takes three parameters, rooms, price and garage. The function uses the this keyword to create an object.

     

    When we call the House function, we assign the result to our variable, which becomes an object.

     

    So, identical code would be:

     

    house1=new Object();

    house1.rooms=4;

    house1.price=100000;

    house1.garage=false;

     

    We would have to type this in for all houses, which would be very tedious and is why we use the class structure instead.

     

    When we display the details for a house, I have introduced the ternary operator, ‘?:’. The ternary operator is a compacted version of:

     

    if (garage) str=’a’; else str=’no’;

     

    (garage?’a’:’no’) means if garage is true, return ‘a’ else return ‘no’. Using the ternary operator removes a line of code, and avoids having to create a new variable.

    Class Methods

     

    The House class we have so far defined only contains object properties. We could add a method to replace the document.write() action we used before. (See example)

     

    <HTML>

    <HEAD>

    <TITLE>Estate Agent 2</TITLE>

    <SCRIPT>

    function House(name,rooms,price,garage) {

    this.name=name;

    this.rooms=rooms;

    this.price=price;

    this.garage=garage;

    this.view=view;

    }

    function view() {

    with (this) document.write(name+’ has ‘+rooms+’ rooms, ‘+(garage?’a’:’no’)+’ garage, and costs £’+price+’<BR>’);

    }

    house1=new House(’House 1′,4,100000,false);

    house2=new House(’Big House’,5,200000,true);

    house1.view();

    house2.view();

    </SCRIPT>

    </HEAD>

    </HTML>

     

    Much better!

     

    Note how we must add another property, name, so that we can identify the house in question. This offers more flexibility than re-using the variable name, and the variable name is inaccessible anyway, i.e. it is very difficult, if not impossible, to get the view() function to use the string ‘house1′.

        

    Q:85 Are namespaces are there in JavaScript?

    A:81 A namespace is a container and allows you to bundle up all your functionality using a unique name. In JavaScript, a namespace is really just an object that you’ve attached all further methods, properties and objects. But it is not always necessary to use namespace.

        

    Q:86 What is JSON? What are the notations used in JSON?

    A:86 JSON (JavaScript Object Notation) is a lightweight data-interchange format. It is easy for humans to read and write. It is easy for machines to parse and generate. It is based on a subset of the JavaScript Programming Language, Standard ECMA-262 3rd Edition – December 1999. JSON is a text format that is completely language independent but uses conventions that are familiar to programmers of the C-family of languages, including C, C++, C#, Java, JavaScript, Perl, Python, and many others. These properties make JSON an ideal data-interchange language.

        

    Q:87 How to get Query String in PHP for http request?

    A:87 $_GET[] and $_REQUEST[]

        

    Q:88 How to get the http Request in PHP?

    A:88 When PHP is used on a Web server to handle a HTTP request, it converts information submitted in the HTTP request as predefined variables:

     

        * $_GET – Associate array of variables submitted with GET method.

        * $_POST – Associate array of variables submitted with POST method.

        * $_COOKIE – Associate array of variables submitted as cookies.

        * $_REQUEST – Associate array of variables from $_GET, $_POST, and $_COOKIE.

        * $_SERVER – Associate array of all information from the server and the HTTP request.

     

        

    Q:89 How you provide security for PHP application?

    A:89 There are many ways to accomplish the security tasks but the most common 7 ways are1. Validate Input. Never trust your user and always filter input before taking it to any operation.2. Provide access control.3. Session ID protection4. preventing Cross Site Scripting (XSS) flaws

     

    5. SQL injection vulnerabilities.

     

    6. Turning off error reporting and exposing to the site for hackers. Instead use log file to catch exceptions

     

    7. Effective Data handling

        

    Q:90 What is SQL Injection in PHP security?

    A:90 SQL injection attacks are extremely simple to defend against, but many applications are still vulnerable. Consider the following SQL statement:

     

    <?php

    $sql = “INSERT

            INTO   users (reg_username,

                          reg_password,

                          reg_email)

            VALUES (‘{$_POST[‘reg_username’]}’,

                    ‘$reg_password’,

                    ‘{$_POST[‘reg_email’]}’)”;

    ?>

     

    This query is constructed with $_POST, which should immediately look suspicious.

     

    Assume that this query is creating a new account. The user provides a desired username and an email address. The registration application generates a temporary password and emails it to the user to verify the email address. Imagine that the user enters the following as a username:

     

    bad_guy’, ‘mypass’, ”), (‘good_guy

     

    This certainly doesn’t look like a valid username, but with no data filtering in place, the application can’t tell. If a valid email address is given (shiflett@php.net, for example), and 1234 is what the application generates for the password, the SQL statement becomes the following:

     

    <?php

     

    $sql = “INSERT

            INTO   users (reg_username,

                          reg_password,

                          reg_email)

            VALUES (‘bad_guy’, ‘mypass’, ”),

              (‘good_guy’,

                    ‘1234’,

                    ‘shiflett@php.net’)”; ?>

     

    Rather than the intended action of creating a single account (good_guy) with a valid email address, the application has been tricked into creating two accounts, and the user supplied every detail of the bad_guy account.

     

    While this particular example might not seem so harmful, it should be clear that worse things could happen once an attacker can make modifications to your SQL statements.

     

    For example, depending on the database you are using, it might be possible to send multiple queries to the database server in a single call. Thus, a user can potentially terminate the existing query with a semicolon and follow this with a query of the user’s choosing.

     

    MySQL, until recently, does not allow multiple queries, so this particular risk is mitigated. Newer versions of MySQL allow multiple queries, but the corresponding PHP extension (ext/mysqli) requires that you use a separate function if you want to send multiple queries (mysqli_multi_query() instead of mysqli_query()). Only allowing a single query is safer, because it limits what an attacker can potentially do.

     

    Protecting against SQL injection is easy:

     

        * Filter your data.This cannot be overstressed. With good data filtering in place, most security concerns are mitigated, and some are practically eliminated.

        * Quote your data.If your database allows it (MySQL does), put single quotes around all values in your SQL statements, regardless of the data type.

        * Escape your data.Sometimes valid data can unintentionally interfere with the format of the SQL statement itself. Use mysql_escape_string() or an escaping function native to your particular database. If there isn’t a specific one, addslashes() is a good last resort.

     

        

    Q:91 What is cross site Scripting?

    A:91 To understand what Cross Site Scripting is, let’s see a usual situation, common to many sites. Let’s say we are taking some information passed in on a querystring (the string after the (?) character within a URL), with the purpose of displaying the content of a variable, for example, the visitor’s name:

     

    http://www.yourdomain.com/welcomedir/welcomepage.php?name=John

    As we can see in this simple querystring, we are passing the visitor’s name as a parameter in the URL, and then displaying it on our “welcomepage.php” page with the following PHP code:

     

    <?php

     

    echo ‘Welcome to our site ’ . stripslashes($_GET[‘name’]);

     

    ?>

    The result of this snippet is shown below:

     

    Welcome to our site John

    This is pretty simple and straightforward. We’re displaying the content of the “name” variable, by using the $_GET superglobal PHP array, as we have done probably hundreds of times. Everything seems to be fine. Now, what’s wrong with this code? Nothing really. But let’s modify the querystring by replacing our visitor’s name passed in the URL:

     

    http://www.yourdomain.com/welcomedir/

    welcomepage.php?name=John

    with something like this:

     

    http://www.yourdomain.com/welcomedir/

    welcomepage.php?name=

    <script language=javascript>alert

    (‘Hey, you are going to be hijacked!’);</script>

    Do you remember the PHP code included in our “welcome.php” page? Yes, you’re correct. When we modify the querystring, the following code is executed:

     

    <?php

     

    echo ‘Welcome to our site ‘ .

    <script language=javascript> alert(‘Hey, you are going

    to be hijacked!’);</script>

     

    ?>

    The output of this code is an alert JavaScript box telling you “Hey, you are going be hijacked!” after the “Welcome to our site” phrase.

     

    Very ugly stuff, right? That’s a simple example of the Cross Site Scripting vulnerability. This means that any pasted JavaScript code into the URL will be executed happily with no complaints at all.

     

        

    Q:92 Which method do you follow to get a record from a million records? (Searching, …. not from database, from an array in php)

    A:92 use array_search(), array_keys(), array_values(), array_key_exists(), and in_array().

        

    Q:93 Which sorting method is lowest time consumable?

    A:93 HeapSort, Merge sort are the lowest time consumable sorting algorithm.

        

    Q:94 Which sorting method is lowest memory consumable?

    A:9412341

    Categories
    MySQL PHP

    Freshers PHP/MySQL Technical Interview Questions & Answers

    Freshers PHP Technical Interview Questions & Answers


    Question : What are the differences between Get and post methods in form submitting. Give the case where we can use get and we can use post methods?
    Answer : When to use GET or POST

    The HTML 2.0 specification says, in section Form Submission (and the HTML 4.0 specification repeats this with minor stylistic changes):

    –>If the processing of a form is idempotent (i.e. it has no lasting observable effect on the state of the
    world), then the form method should be GET. Many database searches have no visible side-effects and make ideal applications of query forms.

    –>If the service associated with the processing of a form has side effects (for example, modification of a database or subscription to a service), the method should be POST.

    How the form data is transmitted?

    quotation from the HTML 4.0 specification

    –> If the method is “get” – -, the user agent takes the value of action, appends a ? to it, then appends the form data set, encoded using the application/x-www-form-urlencoded content type. The user agent then traverses the link to this URI. In this scenario, form data are restricted to ASCII codes.
    –> If the method is “post” –, the user agent conducts an HTTP post transaction using the value of the action attribute and a message created according to the content type specified by the enctype
    attribute.

    Quote from CGI FAQ

    Firstly, the the HTTP protocol specifies differing usages for the two methods. GET requests should always be idempotent on the server. This means that whereas one GET request might (rarely) change some state on the Server, two or more identical requests will have no further effect.

    This is a theoretical point which is also good advice in practice. If a user hits “reload” on his/her browser, an identical request will be sent to the server, potentially resulting in two identical database or guestbook entries, counter increments, etc. Browsers may reload a GET URL automatically, particularly if cacheing is disabled (as is usually the case with CGI output), but will typically prompt the user before re-submitting a POST request. This means you’re far less likely to get inadvertently-repeated entries from POST.

    GET is (in theory) the preferred method for idempotent operations, such as querying a database, though it matters little if you’re using a form. There is a further practical constraint that many systems have built-in limits to the length of a GET request they can handle: when the total size of a request (URL+params) approaches or exceeds 1Kb, you are well-advised to use POST in any
    case.

    I would prefer POST when I don’t want the status to be change when user resubmits. And GET
    when it does not matter.

    Question : Who is the father of PHP and explain the changes in PHP versions?

    Answer : Rasmus Lerdorf is known as the father of PHP.PHP/FI 2.0 is an early and no longer supported version of PHP. PHP 3 is the successor to PHP/FI 2.0 and is a lot nicer. PHP 4 is the current generation of PHP, which uses the Zend engine under the hood. PHP 5 uses Zend engine 2 which, among other things, offers many additional OOPs features.

    Question : How can we submit a form without a submit button?

    Answer : The main idea behind this is to use Java script submit() function in order to submit the form without explicitly clicking any submit button. You can attach the document.formname.submit() method to onclick, onchange events of different inputs and perform the form submission. you
    can even built a timer function where you can automatically submit the form after xx seconds once the loading is done (can be seen in online test sites).

    Question : In how many ways we can retrieve the data in the result set of
    MySQL using PHP?

    Answer : You can do it by 4 Ways

    1. mysql_fetch_row.
    2. mysql_fetch_array
    3. mysql_fetch_object
    4. mysql_fetch_assoc

    Question : What is the difference between mysql_fetch_object and
    mysql_fetch_array?

    Answer : mysql_fetch_object() is similar to mysql_fetch_array(), with one difference –
    an object is returned, instead of an array. Indirectly, that means that you can only access the data by the field names, and not by their offsets (numbers are illegal property names).

    Question : What is the difference between $message and $$message?

    Answer : It is a classic example of PHP’s variable variables. take the following example.

    $message = “Raghav”;

    $$message = “is a owner of http://localhost/wordpress/ “;

    $message is a simple PHP variable that we are used to. But the $$message is not a very familiar face. It creates a variable name $mizan with the value “is a moderator of PHPXperts.” assigned. break it like this${$message} => $mizanSometimes it is convenient to be able to have variable variable names. That is, a variable name which can be set and used dynamically.

    Question : How can we extract string ‘hotmail.com ‘ from a string raghav.cool@hotmail.com using regular expression of PHP?

    Answer : preg_match(”/^http://.+@(.+)$/”,’raghav.cool@hotmail.com’,$found);
    echo $found[1];

    Question : How can we create a database using PHP and MySQL?

    Answer : We can create MySQL Database with the use of mysql_create_db(“Database Name”).

    Question : What are the differences between require and include, include_once and require_once?

    Answer :

    The include() statement includes and evaluates the specified file.The documentation below also applies to require(). The two constructs are identical in every way except how they handle
    failure. include() produces a Warning while require() results in a Fatal Error. In other words, use
    require() if you want a missing file to halt processing of the page. include() does not behave this way, the script will continue regardless. The include_once() statement includes and evaluates the
    specified file during the execution of the script. This is a behavior similar to the include() statement, with the only difference being that if the code from a file has already been included, it will not be
    included again. As the name suggests, it will be included just once.include_once() should be used in cases where the same file might be included and evaluated more than once during a particular execution of a script, and you want to be sure that it is included exactly once to avoid problems with function redefinitions, variable value reassignments, etc. require_once() should be used in cases where the same file might be included and evaluated more than once during a particular execution of a script, and you want to be sure that it is included exactly once to avoid problems with function
    redefinitions, variable value reassignments, etc.

    Question : Can we use include (”abc.PHP”) two times in a PHP page “makeit.PHP”?

    Answer : Yes we can use include() more than one time in any page though it is not a very good practice.

    Question : What are the different tables present in MySQL, which type of table is generated when we are creating a table in the following syntax:
    create table employee (eno int(2),ename varchar(10)) ?

    Answer : Total 5 types of tables we can create
    1. MyISAM
    2. Heap
    3. Merge
    4. INNO DB
    5. ISAM
    MyISAM is the default storage engine as of MySQL 3.23 and as a result if
    we do not specify the table name explicitly it will be assigned to the
    default engine.

    Question : Functions in IMAP, POP3 AND LDAP?

    Answer : You can find these specific information in PHP Manual.

    Question : How can I execute a PHP script using command line?

    Answer : As of version 4.3.0, PHP supports a new SAPI type (Server Application Programming Interface) named CLI which means Command Line Interface. Just run the PHP CLI (Command Line Interface) program and provide the PHP script file name as the command line argument. For example, “php myScript.php”, assuming “php” is the command to invoke the CLI program.
    Be aware that if your PHP script was written for the Web CGI interface, it may not execute properly in command line environment.

    Question : Suppose your Zend engine supports the mode <? ?>. Then how can you
    configure your PHP Zend engine to support <?php ?>mode ?

    Answer : In php.ini file:
    set
    short_open_tag=on
    to make PHP support

    Question : Shopping cart online validation i.e. how can we configure Paypal,
    etc.?

    Answer : We can find the detail documentation about different paypal integration process at the following site PayPal PHP
    SDK : http://www.paypaldev.org/

    Question : What is meant by nl2br()?

    Answer : Inserts HTML line breaks
    (
    )
    before all newlines in a string string nl2br (string); Returns string with ” inserted before all newlines.
    For example: echo nl2br(”god bless/n you”) will output “god bless
    you” to your browser.

    Question : Draw the architecture of Zend engine?

    Answer : The Zend Engine is the internal compiler and runtime engine used by PHP4. Developed by Zeev Suraski and Andi Gutmans, the Zend Engine is an
    abbreviation of their names. In the early days of PHP4, it worked as follows:

    The PHP script was loaded by the Zend Engine and compiled into Zend opcode. Opcodes, short for operation codes, are low level binary instructions. Then the opcode was executed and the HTML generated sent to the client. The opcode was flushed from memory after execution.Today, there are a multitude of products and techniques to help you speed up this process. In the following diagram, we show the how modern PHP scripts work; all the shaded boxes are optional.

    PHP Scripts are loaded into memory and compiled into Zend opcodes.

    Question : What are the current versions of apache, PHP, and MySQL?

    Answer : As of Aug 2008 the current versions are PHP: php5.2.6
    MySQL: MySQL 5.1.2
    Apache: Apache 2.2.9
    Note: visit
    http://www.php.net/,
    http://dev.mysql.com/downloads/mysql/,
    http://www.apache.org/ to get current
    versions.

    Question : What are the reasons for selecting lamp (Linux, apache, MySQL,
    PHP) instead of combination of other software programs, servers and operating systems?

    Answer : All of those are open source resource. Security of Linux is very very more than windows. Apache is a better server that IIS both in functionality and security. MySQL is world most popular open source database. PHP is more faster that asp or any other scripting language.

    Question : How can we encrypt and decrypt a data present in a MySQL table using MySQL?

    Answer : AES_ENCRYPT () and AES_DECRYPT ()

    Question : How can we encrypt the username and password using PHP?

    Answer : The functions in this section perform encryption and decryption, and
    compression and uncompression:

    Encryption Decryption
    AES_ENCRYT() AES_DECRYPT()
    ENCODE() DECODE()
    DES_ENCRYPT() DES_DECRYPT()
    ENCRYPT() Not available
    MD5() Not available
    OLD_PASSWORD() Not available
    PASSWORD() Not available
    SHA() or SHA1() Not available
    Not available UNCOMPRESSED_LENGTH()

    Question : What are the features and advantages of object-oriented programming?

    Answer : One of the main advantages of OO programming is its ease of modification; objects can easily be modified and added to a system there by reducing maintenance costs. OO programming is also considered to be better at modeling the real world than is procedural programming. It allows for more complicated and flexible interactions. OO systems are also easier for non-technical personnel to understand and easier for them to participate in the maintenance and enhancement of a system because it appeals to natural human cognition patterns. For some systems, an OO approach can speed development time since many objects are standard across systems and can be reused. Components that manage dates, shipping, shopping carts, etc. can be purchased and easily modified for a specific system.

    Question : What are the differences between procedure-oriented languages and
    object-oriented languages?

    Answer : Traditional programming has the following characteristics:Functions are written sequentially, so that a change in programming can affect any code that follows it. If a function is used multiple times in a system (i.e., a piece of code that manages the date), it is often simply cut and pasted into each program (i.e., a change log, order function, fulfillment system, etc). If a date change is needed (i.e., Y2K when the code needed to be changed to handle four numerical digits instead of two), all these pieces of code must be found, modified, and tested. Code (sequences of computer instructions) and data (information on which the instructions operates on) are kept separate. Multiple sets of code can access and modify one set of data. One set of code may rely on data in multiple places. Multiple sets of code and data are required to work together. Changes made to any of the code sets and data sets can cause problems through out the system.Object-Oriented programming takes a radically different approach:Code and data are merged into one indivisible item – an object (the term “component” has also been used to describe an object.) An object is an abstraction of a set of real-world things (for example, an object may be created around “date”) The object would contain all information and
    functionality for that thing (A date object it may contain labels like January, February, Tuesday, Wednesday.
    It may contain functionality that manages leap years, determines if it is a business day or a holiday, etc., See Fig. 1). Ideally, information about a particular thing should reside in only one place in a system.The information within an object is encapsulated (or hidden) from the rest of the system. A system is composed of multiple objects (i.e., date function, reports, order processing, etc., See Fig 2). When one object needs information from another object, a request is sent asking for specific information. (for example, a report object may need to know what today’s date is and will send a request to the date object) These requests are called messages and each object has an interface that manages messages. OO programming languages include features such as “class”, “instance”, “inheritance”, and “polymorphism” that increase the power and
    flexibility of an object.

    Question : What is the use of friend function?

    Answer : Sometimes a function is best shared among a number of different classes. Such functions can be declared either as member functions of one class or as global functions. In either case they can be set to be friends of other classes, by using a friend specifier in the class that is admitting them. Such functions can use all attributes of the class which names them as a friend, as if they were themselves members of that class. A friend declaration is essentially a prototype for a member function, but instead of requiring an implementation with the name of that class attached by the double colon syntax, a global function or member function of another class provides the match.

    Question : What are the differences between public, private, protected,static, transient, final and volatile?

    Answer : Public: Public declared items can be accessed everywhere.
    Protected: Protected limits access to inherited and parent classes (and to the class that defines the item).
    Private: Private limits visibility only to the class that defines the item.
    Static: A static variable exists only in a local function scope, but it does not lose its value when program execution leaves this scope.
    Final: Final keyword prevents child classes from overriding a method by prefixing the definition with final. If the class itself is being defined final then it cannot be extended.
    Transient: A transient variable is a variable that may not be serialized.
    Volatile: a variable that might be concurrently modified by multiple threads should be declared volatile. Variables declared to be volatile will not be optimized by the compiler because their value can change at any time.

    Question : What are the different types of errors in PHP?

    Answer : Three are three types of errors:1. Notices: These are trivial, non-critical errors that PHP encounters while executing a script – for example, accessing a variable that has not yet been defined. By default, such errors are not displayed to the user at all – although, as you will see, you can change this default behavior.2. Warnings: These are more serious errors – for example, attempting to include() a file which does not exist. By default, these errors are displayed to the user, but they do not result in script termination.3. Fatal errors: These are critical errors – for example,
    instantiating an object of a non-existent class, or calling a non-existent function. These errors cause the immediate termination of the script, and PHP’s default behavior is to display them to the user when they take place.

    Question : What is the functionality of the function strstr and stristr?

    Answer : strstr:
    Returns part of haystack string from the first occurrence of needle to the end of haystack.If needle is not found, returns FALSE. If needle is not a string, it is converted to an integer and applied as the ordinal value of a character. This function is case-sensitive. For case-insensitive searches, use stristr().

    Question : What are the differences between PHP 3 and PHP 4 and PHP 5?

    Answer : PHP 3 is most procedure oriented and , PHP4 and PHP5 aer object oriented. For more details
    http://php.net/

    Question : How can we convert asp pages to PHP pages?

    Answer : There are lots of tools available for asp to PHP conversion. you can search Google for that. the best one is available at http://asp2php.naken.cc/

    Question : What is the functionality of the function htmlentities?

    Answer : Convert all applicable characters to HTML entities
    This function is identical to htmlspecialchars() in all ways, except with htmlentities(), all characters which have HTML character entity equivalents are translated into these entities.

    Question : How can we get second of the current time using date function?

    Answer : $second = date(”s”);

    Question : How can we convert the time zones using PHP?

    Answer : By using date_default_timezone_get and
    date_default_timezone_set function on PHP 5.1.0
    <!–p// Discover what 8am in Tokyo relates to on the East Coast of the US
    // Set the default timezone to Tokyo time:
    date_default_timezone_set(’Asia/Tokyo’);
    // Now generate the timestamp for that particular timezone, on Jan 1st, 2000
    $stamp = mktime(8, 0, 0, 1, 1, 2000);
    // Now set the timezone back to US/Eastern
    date_default_timezone_set(’US/Eastern’);
    // Output the date in a standard format (RFC1123), this will  print:
    // Fri, 31 Dec 1999 18:00:00 EST
    echo ‘
    ‘, date(DATE_RFC1123, $stamp) ,’
    ‘; ?>

    Question : What is meant by urlencode and urldecode?

    Answer : URLencode returns a string in which all non-alphanumeric characters except -_. have been replaced with a percent (%) sign followed by two hex digits and spaces encoded as plus (+) signs. It is encoded the same way that the posted data from a WWW form
    is encoded, that is the same way as in application/x-www-form-urlencoded media type. urldecode decodes any %## encoding in the given string.

    Question : What is the difference between the functions unlink and unset?

    Answer : unlink() deletes the given file from the file system.
    unset() makes a variable undefined.

    Question : How can we register the variables into a session?

    Answer : $_SESSION[’name’] = “RAGHAV”;

    Question : How can we get the properties (size, type, width, height) of an image using PHP image functions?

    Answer : To know the Image type use exif_imagetype () function
    To know the Image size use getimagesize () function
    To know the image width use imagesx () function
    To know the image height use imagesy() function

    Question : How can we get the browser properties using PHP?

    Answer : By using
    $_SERVER[’HTTP_USER_AGENT’] variable.

    Question : What is the maximum size of a file that can be uploaded using PHP
    and how can we change this?

    Answer : By default the maximum size is 2MB. and we can change the following setup at php.iniupload_max_filesize = 2M

    Question : How can we increase the execution time of a PHP script?

    Answer : by changing the following setup at php.inimax_execution_time = 30; Maximum execution time of each script, in seconds

    Question : How can we take a backup of a MySQL table and how can we restore it. ?

    Answer : To backup: BACKUP TABLE tbl_name[,tbl_name…] TO ‘/path/to/backup/directory’
    RESTORE TABLE tbl_name[,tbl_name…] FROM ‘/path/to/backup/directory’mysqldump: Dumping Table Structure and DataUtility to dump a database or a collection of database for backup or for transferring the data to another SQL server (not necessarily a MySQL server). The dump will contain SQL statements to create the table and/or populate the table. -t, –no-create-info Don’t write table creation information (the CREATE TABLE statement). -d, –no-data Don’t write any row information for the table. This is very useful if you just want to get a dump of the structure for a table!

    Question : How can we optimize or increase the speed of a MySQL select query?

    Answer : • First of all instead of using select * from table1, use select column1, column2, column3.. from table1
    •Look for the opportunity to introduce index in the table you are  querying.
    •use limit keyword if you are looking for any specific number of rows from the result set.

    Question : How many ways can we get the value of current session id?

    Answer : session_id() returns the session id for the current session.

    Question : How can we destroy the session, how can we unset the variable of a session?

    Answer : session_unregister — Unregister a global variable from the current session

    session_unset — Free all session variables

    Question : How can we destroy the cookie?

    Answer : Set the cookie in past.

    Question : How many ways we can pass the variable through the navigation between the pages?

    Answer : •GET/QueryString
    •POST

    Question : What is the difference between ereg_replace() and eregi_replace()?

    Answer : eregi_replace() function is identical to ereg_replace() except that this ignores case distinction when matching alphabetic characters.eregi_replace() function is identical to ereg_replace() except that this ignores case distinction when matching alphabetic characters.

    Question : What are the different functions in sorting an array?

    Answer : Sort(), arsort(),
    asort(), ksort(),
    natsort(), natcasesort(),
    rsort(), usort(),
    array_multisort(), and
    uksort().

    Question : How can we know the count/number of elements of an array?

    Answer : 2 ways
    a) sizeof($urarray) This function is an alias of count()
    b) count($urarray)

    Question : What is the PHP predefined variable that tells the What types of
    images that PHP supports?

    Answer : Though i am not sure if this is wrong or not, With the exif extension you are able to work with image meta data.

    Question : How can I know that a variable is a number or not using a JavaScript?

    Answer : bool is_numeric ( mixed var) Returns TRUE if var is a number or a numeric string, FALSE otherwise.or use isNaN(mixed var)The isNaN() function is used to check if a value is not a number.

    Question : List out some tools through which we can draw E-R diagrams for mysql.

    Answer :
    Case Studio
    Smart Draw

    Question : How can I retrieve values from one database server and store themin other database server using PHP?

    Answer : WeWe can always fetch from one database and rewrite to another. Here is a nice solution of it.
    $db1 = mysql_connect(”host”,”user”,”pwd”);
    mysql_select_db(”db1?, $db1);
    $res1 = mysql_query(”query”,$db1);
    $db2 = mysql_connect(”host”,”user”,”pwd”);
    mysql_select_db(”db2?, $db2);
    $res2 = mysql_query(”query”,$db2);
    At this point you can only fetch records from you previous ResultSet, i.e $res1 – But you cannot execute new query in $db1, even if yousupply the link as because the link was overwritten by the new db.so at this point the following script will fail
    $res3 = mysql_query(”query”,$db1); //this will failSo how to solve that? take a look below.
    $db1 = mysql_connect(”host”,”user”,”pwd”);
    mysql_select_db(”db1?, $db1);
    $res1 = mysql_query(”query”,$db1);
    $db2 = mysql_connect(”host”,”user”,”pwd”, true);
    mysql_select_db(”db2?, $db2);
    $res2 = mysql_query(”query”,$db2);
    So mysql_connect has another optional boolean parameter whichindicates whether a link will be created or not. As we connect to the $db2 with this optional parameter set to ‘true’, so both link willremain live. Now the following query will execute successfully.
    $res3 = mysql_query(”query”,$db1);

    Question : List out the predefined classes in PHP?

    Answer : Directory
    stdClass
    __PHP_Incomplete_Class
    exception
    php_user_filter

    Question : How can I make a script that can be bi-language (supports  English, German)?

    Answer : You can maintain two separate language file for each of the language. All the labels are putted in both language files as variables and assign those variables in the PHP source. On run-time choose the required language option.

    Question : What are the difference between abstract class and interface?

    Answer : Abstract class: abstract classes are the class where one or moremethods are abstract but not necessarily all method has to be abstract.

    Abstract methods are the methods, which are declare in its class but not defined. The definition of those methods must be in its extending class.

    Interface: Interfaces are one type of class where all the methods are abstract. That means all the methods only declared but not defined. All the methods must be defined by its implemented class.

    Question : How can we send mail using JavaScript?

    Answer : JavaScript does not have any networking capabilities as it isdesigned to work on client site. As a result we can not send mails usingJavaScript. But we can call the client side mail protocol mailtovia JavaScript to prompt for an Email  to send. this requires the client to approve it.

    Question : How can we repair a MySQL table?

    Answer : The syntex for repairing a MySQL table is REPAIR TABLENAME, [TABLENAME, ], [Quick],[Extended].This command will repair the table specified if the quick is given the MySQL will do a repair of only the index tree if the extended is givenit will create index row by row.

    Question : What are the advantages of stored procedures, triggers, indexes?

    Answer : A stored procedure is a set of SQL commands that can be compiled andstored in the server. Once this has been done, clients don’t need tokeep re-issuing the entire query but can refer to the stored procedure.This provides better overall performance because the query has to beparsed only once, and less information needs to be sent between theserver and the client. You can also raise the conceptual level by havinglibraries of functions in the server. However, stored procedures ofcourse do increase the load on the database server system, as more of the work is done on the server side and less on the client (application)side.Triggers will also be implemented. A trigger is effectively a type of stored procedure, one that is invoked when a particular event occurs.For example, you can install a stored procedure that is triggered each time a record is deleted from a transaction table and that stored procedure automatically deletes the corresponding customer from a customer table when all his transactions are deleted.Indexes are used to find rows with specific column values quickly.Without an index, MySQL must begin with the first row and then read through the entire table to find the relevant rows. The larger the table, the more this costs. If the table has an index for the columns in question, MySQL can quickly determine the position to seek to in the middle of the data file without having to look at all the data. If a table has 1,000 rows, this is at least 100 times faster than reading sequentially. If you need to access most of the rows, it is faster to read sequentially, because this minimizes disk seeks.

    Question : What is the maximum length of a table name, database name and field name in MySQL?

    Answer : The following table describes the maximum length for each type of identifier.

    Identifier Maximum Length(bytes)
    Database 64
    Table 64
    Column 64
    Index 64
    Alias 255

    There are some restrictions on the characters that may appear in identifiers.

    Question : How many values can the SET function of MySQL take?

    Answer : MySQL set can take zero or more values but at the maximum it can take 64 values.

    Question : What are the other commands to know the structure of table using MySQL commands except explain command?

    Answer : describe Table-Name;

    Question : How many tables will create when we create table, what are they?

    Answer : The ‘.frm’ file stores the table definition.The data file has a ‘.MYD’ (MYData) extension.The index file has a ‘.MYI’ (MYIndex) extension.

    Question : What is the purpose of the following files having extensions 1) .frm2) .myd 3) .myi? What do these files contain?

    Answer : In MySql, the default table type is MyISAM.Each MyISAM table is stored on disk in three files. The files have names that begin with the table name and have an extension to indicate the file type.The ‘.frm’ file stores the table definition.The data file has a ‘.MYD’ (MYData) extension.The index file has a ‘.MYI’ (MYIndex) extension.

    Question : What is maximum size of a database in MySQL?

    Answer : If the operating system or file system places a limit on the number of files in a directory, MySQL is bound by that constraint.The efficiency of the operating system in handling large numbers offiles in a directory can place a practical limit on the number of tables in a database. If the time required to open a file in the directory increases significantly as the number of files increases, database performance can be adversely affected.The amount of available disk space limits the number of tables.MySQL 3.22 had a 4GB (4 gigabyte) limit on table size. With the MyISAM storage engine in MySQL 3.23, the maximum table size was increased to65536 terabytes (2567 – 1 bytes). With this larger allowed table size,the maximum effective table size for MySQL databases is usually determined by operating system constraints on file sizes, not by MySQL internal limits.The InnoDB storage engine maintains InnoDB tables within a table space that can be created from several files. This allows a table to exceed the maximum individual file size. The table space can include raw disk partitions, which allows extremely large tables. The maximum table space size is 64TB.The following table lists some examples of operating system file-size limits. This is only a rough guide and is not intended to be definitive.For the most up-to-date information, be sure to check the documentationspecific to your operating system.Operating System File-size Limit Linux 2.2-Intel 32-bit 2GB (LFS: 4GB)
    Linux 2.4+ (using ext3 filesystem) 4TB
    Solaris 9/10 16TB
    NetWare w/NSS filesystem 8TB
    Win32 w/ FAT/FAT32 2GB/4GB
    Win32 w/ NTFS 2TB (possibly larger)
    MacOS X w/ HFS+ 2TB

    Question : Give the syntax of Grant and Revoke commands?

    Answer : The generic syntax for grant is as following :
    > GRANT [rights] on [database/s] TO [username@hostname] IDENTIFIED BY[password]now rights can be a) All privileges b) combination of create, drop, select, insert, update and delete etc. We can grant rights on all databse by using *.* or some specificdatabase by database.* or a specific table by database.table_name username@hotsname can be either username@localhost, username@hostname and username@% where hostname is any valid hostname and % represents any name, the *.*any condition password is simply the password of user.
    The generic syntax for revoke is as following :
    > REVOKE [rights] on [database/s] FROM [username@hostname] now rights can be as explained above a) All privileges b) combination of create, drop, select, insert, update and delete etc.username@hotsname can be either username@localhost, username@hostname and username@% where hostname is any valid hostname and % represents any name, the *.*any condition

    Question : Explain Normalization concept?

    Answer : The normalization process involves getting our data to conform to three progressive normal forms, and a higher level of normalization cannot be achieved until the previous levels have been achieved (there are actually five normal forms, but the last two are mainly academic and will not be discussed).First Normal Form  The First Normal Form (or 1NF) involves removal of redundant data from horizontal rows. We want to ensure that there is no duplication of data in a given row, and that every column stores the least amount of information possible (making the field atomic). Second Normal Form Where the First Normal Form deals with redundancy of data across a horizontal row, Second Normal Form (or 2NF) deals with redundancy of data in vertical columns. As stated earlier, the normal forms are progressive, so to achieve Second Normal Form, your tables must already be in First Normal Form.Third Normal Form I have a confession to make; I do not often use Third Normal Form. In Third Normal Form we are looking for data in our tables that is not fully dependent on the primary key, but dependent on another value in the table.

    Question : How can we find the number of rows in a table using MySQL?

    Answer : Use this for mysql>SELECT COUNT(*) FROM table_name;

    Question : How can we find the number of rows in a result set using PHP?

    Answer :
    $result = mysql_query($sql, $db_link);
    $num_rows = mysql_num_rows($result);
    echo “$num_rows rows found”;

    Question : How many ways we can we find the current date using MySQL?

    Answer :
    SELECT CURDATE();
    CURRENT_DATE() = CURDATE()
    for time use SELECT CURTIME();
    CURRENT_TIME() = CURTIME()

    Question : What are the advantages and disadvantages of Cascading Style Sheets?

    Answer :
    External Style Sheets
    Advantages : Can control styles for multiple documents at once. Classes can be created for use on multiple HTML element types in many documents.Selector and grouping methods can be used to apply styles under complex contexts.
    Disadvantages : An extra download is required to import style information for eachdocument The rendering of the document may be delayed until the externalstyle sheet is loaded becomes slightly unwieldy for small quantities ofstyle definitions.
    Embedded Style Sheets
    Advantages : Classes can be created for use on multiple tag types in the document.Selector and grouping methods can be used to apply styles under complexcontexts. No additional downloads necessary to receive style information.
    Disadvantages : This method can not control styles for multiple documents at once.
    Inline Styles
    Advantages : Useful for small quantities of style definitions. Can override otherstyle specification methods at the local level so only exceptions needto be listed in conjunction with other style methods.
    Disadvantages : Does not distance style information from content (a main goal ofSGML/HTML). Can not control styles for multiple documents at once.Author can not create or control classes of elements to control multipleelement types within the document. Selector grouping methods can not beused to create complex element addressing scenarios

    Question : What type of inheritance that PHP supports?

    Answer : In PHP an extended class is always dependent on a single base class,that is, multiple inheritance is supported by interfaces. Classes are extended using the keyword ‘extends’.

    Question : What is the difference between Primary Key and Unique key?

    Answer : Primary Key: A column in a table whose values uniquely identify therows in the table. A primary key value cannot be NULL. Unique Key: Unique Keys are used to uniquely identify each row in thetable. There can be one and only one row for each unique key value. So NULL can be a unique key.There can be only one primary key for a table but there can be morethan one unique for a table.

    Question : The structure of table view buyers is as follows:

    Field Type Null Key Default Extra
    user_pri_id int(15) PRI null auto_increment
    userid varchar(10) YES null

    the value of user_pri_id the last row 999 then What will happen inthe following conditions?Condition1: Delete all the rows and insert another row then.What is the starting value for this auto incremented field user_pri_id ,Condition2: Delete the last row(having the field value 999) andinsert another row then. What is the value for this auto incremented field user_pri_id.

    Answer : In both cases let the value for auto increment field be n then nextrow will have value n+1 i.e. 1000.

    Question : What are the advantages/disadvantages of MySQL and PHP?

    Answer : Both of them are open source software (so free of cost), supportcross platform. php is faster then ASP and JSP.

    Question : What is the difference between GROUP BY and ORDER BY in Sql?

    Answer : ORDER BY [col1],[col2],…,[coln]; Tells DBMS according to what columns it should sort the result. If two rows will have the same value in col1it will try to sort them according to col2 and so on.GROUP BY[col1],[col2],…,[coln]; Tells DBMS to group results with same value of column col1. You can use COUNT(col1), SUM(col1), AVG(col1) with it, if you want to count all items in group, sum all values or view average.

    Question : What is the difference between char and varchar data types?

    Answer : Set char to occupy n bytes and it will take n bytes even if u r storing a value of n-m bytes Set varchar to occupy n bytes and it will take only the required space and will not use the n bytes eg. name char(15) will waste 10 bytes if we store ‘mizan’, if each char takes a byte eg. name varchar(15) will just use 5 bytes if we store ‘mizan’, if each char takes a byte. rest 10 bytes will be free.

    Question : What is the functionality of md5 function in PHP?

    Answer : Calculate the md5 hash of a string. The hash is a 32-characterhexadecimal number. I use it to generate keys which I use to identifyusers etc. If I add random no techniques to it the md5 generated nowwill be totally different for the same string I am using.

    Question : How can I load data from a text file into a table?

    Answer : you can use LOAD DATA INFILE file_name; syntax to load datafrom a text file. but you have to make sure thata) data is delimitedb) columns and data matched correctly.

    Question : How can we know the number of days between two given dates using MySQL?

    Answer : SELECT DATEDIFF(’2007-03-07?,’2005-01-01?);

    Question : How can we know the number of days between two given dates using PHP?

    Answer : $date1 = date(’Y-m-d’);
    $date2 = ‘2006-08-15?;
    $days = (strtotime($date1) – strtotime($date2)) / (60 * 60 * 24);