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PHP Sessions

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Release： 2016-07-29 08:58:14

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PHP Sessions

PHP session variables are used to store information about the user session (session), or to change the settings of the user session (session). Session variables store information for a single user and are available to all pages in the application.

PHP Session Variables

When you work on an application on your computer, you open it, make changes, and then close it. It's a lot like a conversation. The computer knows who you are. It knows when you open and close apps. However, on the Internet a problem arises: since HTTP addresses cannot maintain state, the web server has no idea who you are and what you do.
PHP sessions solve this problem by storing user information on the server for subsequent use (such as user name, purchased items, etc.). However, session information is temporary and will be deleted after the user leaves the site. If you need to store information permanently, you can store the data in a database.
Session works by creating a unique id (UID) for each visitor and storing variables based on this UID. The UID is stored in a cookie or passed through the URL.

Start PHP Session

Before you can store user information in a PHP session, you must first start the session.
Note: The session_start() function must be placed before the tag:

<code><span><span><?php session_start(); ?></span></span><span><<span>html</span>></span><span><<span>body</span>></span><span></<span>body</span>></span><span></<span>html</span>></span></code>

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The above code will register the user's session with the server so that you can start saving user information, and will assign a UID to the user's session.

Storing Session Variables

The correct way to store and retrieve session variables is to use the PHP $_SESSION variable:

Destroy Session

If you wish to delete some session data, you can use unset() or session_destroy( ) function.
The unset() function is used to release the specified session variable:

<code><span><?php</span>
session_start();
<span>if</span>(<span>isset</span>(<span>$_SESSION</span>[<span>'views'</span>]))
<span>unset</span>(<span>$_SESSION</span>[<span>'views'</span>]);
<span>?></span></code>

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You can also completely destroy the session by calling the session_destroy() function:

<code><span><?php</span>
session_destroy();
<span>?></span></code>

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Note: session_destroy() will reset the session and you will lose all stored session data .

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The above has introduced PHP Sessions, including aspects of it. I hope it will be helpful to friends who are interested in PHP tutorials.