What is SESSION ?
- A session is a mechanism to persist information across the different web pages to identify users as they navigate a site or app
- A PHP session stores data on the server rather than user's computer.
- In a session based environment, every user is identified through a unique number called session identifier or SID.
- The session IDs are randomly generated by the PHP engine
Starting a PHP Session
To begin a new session, simply call the PHP
session_start() function. It will create a new session and generate a unique session ID for the user.<?php
// Starting session
session_start();
?> Firstly,
session_start() function checks to see if a
session already exists by presence of a session ID. If session id exists, then it sets up the
session variables and if doesn't, it starts a new session by creating a
new session ID.You must call the
session_start() function at the beginning
of the page.Storing and Accessing Session Data
You can store all your session data as key-value pairs in the
$_SESSION[] superglobal array. <?php
// Starting session
session_start();
// Storing session data
$_SESSION["firstname"] = "Shobhit";
$_SESSION["lastname"] = "Garg";
?>To access the session data
<?php
// Starting session
session_start();
// Accessing session data
echo 'Hi, ' . $_SESSION["firstname"] . ' ' . $_SESSION["lastname"];
?> Destroying a session
If you want to remove certain session data:
<?php
// Starting session
session_start();
// Removing session data
if(isset($_SESSION["lastname"])){
unset($_SESSION["lastname"]);
}
?> <?php
// Starting session
session_start();
// Destroying session
session_destroy();
?>
