PHP Questions

Questions : which mysql data type you use for storing images.
Answers: BLOB (Images are stored as binary in mysql).

Question:How you will decrypt the password using md5();
Answer:You cann’y decrypt using md5 function because it is 1-way encryption algorithm.

Question:Name other1-way encryption algorithm.
Answer:SHA

Question:list types of joins in mysql.
Answer:Inner join,Left outer join and right outer join.

Question:What is difference between mysql_connect and mysql_pconnect.
Answer:
mysql_connect : The connection object is created on every request and destroyed once the request is completed.
mysql_pconnect: pconnect stands for persistence connection. i.e when the connection object is release it is not destroyed rather it is kept in pool for other request to use.

PHP Questions

What’s PHP ?
The PHP Hypertext Preprocessor is a programming language that allows web developers to create dynamic content that interacts with databases. PHP is basically used for developing web based software applications.

What Is a Session?
A session is a logical object created by the PHP engine to allow you to preserve data across subsequent HTTP requests.

There is only one session object available to your PHP scripts at any time. Data saved to the session by a script can be retrieved by the same script or another script when requested from the same visitor.

Sessions are commonly used to store temporary data to allow multiple PHP pages to offer a complete functional transaction for the same visitor.

What is meant by PEAR in php?
Answer1:
PEAR is the next revolution in PHP. This repository is bringing higher level programming to PHP. PEAR is a framework and distribution system for reusable PHP components. It eases installation by bringing an automated wizard, and packing the strength and experience of PHP users into a nicely organised OOP library. PEAR also provides a command-line interface that can be used to automatically install “packages”
Answer2:
PEAR is short for “PHP Extension and Application Repository” and is pronounced just like the fruit. The purpose of PEAR is to provide:
A structured library of open-sourced code for PHP users
A system for code distribution and package maintenance
A standard style for code written in PHP
The PHP Foundation Classes (PFC),
The PHP Extension Community Library (PECL),
A web site, mailing lists and download mirrors to support the PHP/PEAR community
PEAR is a community-driven project with the PEAR Group as the governing body. The project has been founded by Stig S. Bakken in 1999 and quite a lot of people have joined the project since then.

How can we know the number of days between two given dates using PHP?
Simple arithmetic:
$date1 = date(’Y-m-d’);
$date2 = ‘2006-07-01′;
$days = (strtotime() – strtotime()) / (60 * 60 * 24);
echo “Number of days since ‘2006-07-01′: $days”;

How can we repair a MySQL table?

The syntex for repairing a mysql table is:
REPAIR TABLE tablename
REPAIR TABLE tablename QUICK
REPAIR TABLE tablename EXTENDED
This command will repair the table specified.
If QUICK is given, MySQL will do a repair of only the index tree.
If EXTENDED is given, it will create index row by row.

What is the difference between $message and $$message?
Anwser 1:
$message is a simple variable whereas $$message is a reference variable. Example:
$user = ‘bob’
is equivalent to
$holder = ‘user’;
$$holder = ‘bob’;

Anwser 2:
They are both variables. But $message is a variable with a fixed name. $$message is a variable who’s name is stored in $message. For example, if $message contains “var”, $$message is the same as $var.

PHP Design Patterns PHP Job Interview Questions

As a PHP contractor, consultant, and freelancer I’ve had a fair number of interviews – and sometimes I have been asked technical questions. Here are a few to help you prepare for your next PHP job interview.

=,==,=== – 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 crypt() function can be used to encrypt data. (Honestly, the one time I had this question I drew a complete blank on the function name, 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. I use Eclipse 3.1 with PHP extensions, and interviewers seem to like that. There are probably others such as Zend Studio that are also fine answers. Serious Unix users would be good with vi or emacs.

PHP Statics, 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.