PHP-MYSQL Interview Questions and Answers

Posted: February 25, 2011 in Uncategorized

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

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

What is the difference between mysql_fetch_object and mysql_fetch_array?

MySQL fetch object will collect first single matching record where mysql_fetch_array will collect all matching records from the table in an array

What is meant by urlencode and urldecode?

Anwser 1:
urlencode() returns the URL encoded version of the given string. URL coding converts special characters into % signs followed by two hex digits. For example: urlencode(“10.00%”) will return “10%2E00%25”. URL encoded strings are safe to be used as part of URLs.
urldecode() returns the URL decoded version of the given string.

Anwser 2:
string urlencode(str) – Returns the URL encoded version of the input string. String values to be used in URL query string need to be URL encoded. In the URL encoded version:

Alphanumeric characters are maintained as is.
Space characters are converted to “+” characters.
Other non-alphanumeric characters are converted “%” followed by two hex digits representing the converted character.

string urldecode(str) – Returns the original string of the input URL encoded string.

For example:

$discount =”10.00%”;
$url = “http://domain.com/submit.php?disc=”.urlencode($discount);
echo $url;

You will get “http://domain.com/submit.php?disc=10%2E00%25”.

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.

What does a special set of tags do in PHP?

What does a special set of tags <?= and ?> do in PHP?
The output is displayed directly to the browser.

What Is a Persistent Cookie?

A persistent cookie is a cookie which is stored in a cookie file permanently on the browser’s computer. By default, cookies are created as temporary cookies which stored only in the browser’s memory. When the browser is closed, temporary cookies will be erased. You should decide when to use temporary cookies and when to use persistent cookies based on their differences:

  • Temporary cookies can not be used for tracking long-term information.
  • Persistent cookies can be used for tracking long-term information.
  • Temporary cookies are safer because no programs other than the browser can access them.
  • Persistent cookies are less secure because users can open cookie files see the cookie values

How can we encrypt the username and password using PHP?

Answer1
You can encrypt a password with the following Mysql>SET PASSWORD=PASSWORD(“Password”);

Answer2
You can use the MySQL PASSWORD() function to encrypt username and password. For example,
INSERT into user (password, …) VALUES (PASSWORD($password”)), …);

How do I find out the number of parameters passed into function. ?

func_num_args() function returns the number of parameters passed in.

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