For details on how to use php session, see: php session session topic
* session session
* session is very similar to cookie, It just saves the user data to the page on the server
* But the query key is still on the browser, saved with a special cookie
* This special key is called: PHPSESSID( Session ID)
//The session must be opened before all html code is output to the browser
//session_start() will send a 32-bit hexadecimal PHPSESSID# to the browser
##//There must be no statements such as echo, print, include, or even blank lines before opening a session
session_start();
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//Once the session is opened successfully, we can save the user's session information On the server
//All operations of the session are implemented through the super global variable $_SESSION
$_SESSION['user_name'] = 'admin';
$_SESSION['user_id'] = 1;
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//Tmp/php/32-bit text file corresponding to PHPSESSID on the server
//user_name|s:5:"admin";user_id|i:1;
//Syntax: variable name|type: value; use a semicolon between each session variable separated, the string type will have a length prompt
//Session access is very similar to cookies, use the $_SESSION array directly
echo $_SESSION['user_name'];
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//Update
$_SESSION['user_name'] = 'peter';
echo $_SESSION['user_name'];
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//Delete
//1. Delete a single session variable
unset($_SESSION['user_id']);
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//2. Delete all session variables and clear the contents of the session file on the server
$_SESSION = [];
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//3. Clear For all user sessions, delete the session files on the server
session_destroy();
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//If you want to completely delete the session, the cookie corresponding to the PHPSESSID on the browser should also be deleted
//Execute , there can be no more setting statements in front, otherwise a PHPSESSID will be regenerated
setcookie('PHPSESSID', '', time()-3600);
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//Summary: Correct and safe deletion of session should include the following three steps:
$_SESSION = []; //清空当前用户的所有会话信息
session_destroy(); //清空当前域名下所有的会话信息
setcookie('PHPSESSID', '', time()-3600); //删除保存在客户端上的会话id
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