PHP Sessions - How to Create, Access and Destroy Sessions in PHP

• In general, session refers to a frame of communication between two medium. A PHP session is used to store data on a server rather than the computer of the user. Session identifiers or SID is a unique number which is used to identify every user in a session based environment. The SID is used to link the user with his information on the server like posts, emails etc.

Starting a PHP Session

• The first step is to start up a session. After a session is started, session variables can be created to store information.
• The PHP session_start() function is used to begin a new session.It also creates a new session ID for the user.

Sample Code

<?php

session_start();

?>

Storing Session Data

• Session data in key-value pairs using the $_SESSION[ ] superglobal array.The stored data can be accessed during lifetime of a session.

<?php

session_start();

$_SESSION["Id"] = "29";
$_SESSION["Name"] = "Wikitechy";

?>

Accessing Session Data

• Data stored in sessions can be easily accessed by firstly calling session_start() and then by passing the corresponding key to the $_SESSION associative array.

Sample Code

<?php
session_start();
echo 'The Name of the student is :' . $_SESSION["Name"] . '<br>';
echo 'The Id of the student is :' . $_SESSION["Id"] . '<br>';

?>

Destroying Certain Session Data

• To delete only a certain session data,the unset feature can be used with the corresponding session variable in the $_SESSION associative array.

<?php

session_start();

if(isset($_SESSION["Name"])){
	unset($_SESSION["Id"]);
}

?>

Destroying Complete Session

• The session_destroy() function is used to completely destroy a session. The session_destroy() function does not require any argument.

<?php

session_start();
session_destroy();

?>

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