What are the Differences Between session_unset() and session_destroy() in PHP?

Delving into the Distinction between session_unset() and session_destroy() in PHP

PHP's session management system offers two primary functions for manipulating session data: session_unset() and session_destroy(). While their names may suggest a shared purpose, a closer examination reveals distinct roles and implications.

Unraveling the Differences

• session_unset(): This function frees all variables associated with the current session, effectively emptying the $_SESSION array. It does not, however, affect the stored session data on the server. Think of it as wiping the slate clean locally.
• session_destroy(): In contrast to session_unset(), this function eliminates the session data stored on the server (for example, in a file or database). It also clears the session ID and all session variables at both the server and the client. This function effectively terminates a user's session.

Preserving the Session Cookie

It's important to note that neither session_unset() nor session_destroy() deletes the session cookie on the client's browser. The session cookie is only set to expire when the user closes their browser or the session expires based on its configured timeout.

To explicitly destroy a session, including the session cookie, follow these steps:

1. Invoke session_destroy() to terminate the session.
2. Call setcookie() to delete the session cookie: setcookie('PHPSESSID', '', time()-3600);

By carrying out these steps, you can completely remove all traces of a session.

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