How to operate MySQL database and session dialogue in PHP

This article mainly introduces the method of using PHP to operate MySQL database and session dialogue. Friends who are interested can refer to it. I hope it will be helpful to everyone.

The example in this article describes how PHP uses MySQL to save sessions. The specific analysis is as follows:

This function is generally found in many large systems, but it must be separated and analyzed. It is reliable online. There is not much information. Here I compiled an article to share with you.

Using MySQL to save sessions has many advantages over files:

1) It is beneficial to distributed systems. Files only Can be saved on one machine
2) It is beneficial to systems with large traffic. When using files, each session is saved in a file. The directory will be very large and it will be difficult to find the session file.

//////使用MySQL保存会话首先要创建session表：
<?php
$hostname_login = "localhost"; // Server address
$username_login = "root"; // User name 
$password_login = ""; // Password
//
$data_name = "session"; // Database name
$login = mysql_pconnect($hostname_login, $username_login, $password_login) or trigger_error(mysql_error(),E_USER_ERROR); 
$sql="SHOW DATABASES LIKE &#39;".$data_name."&#39;"; // If it is exist
if($rs_table=mysql_query($sql,$login)) { 
 if($rs_value=mysql_fetch_array($rs_table)) { 
  echo "数据库已经存在！\n!";
  exit(); 
 } 
}
$sql="CREATE DATABASE $data_name";  
mysql_query($sql); // Crate database
echo "数据库创建成功！\n"; 
mysql_select_db($data_name, $login);
$sql="CREATE TABLE `sessions` ( 
`SessionKey` varchar(32) NOT NULL default &#39;&#39;, 
`SessionArray` blob NOT NULL, 
`SessionExpTime` int(20) unsigned NOT NULL default &#39;0&#39;, 
PRIMARY KEY (`SessionKey`), 
KEY `SessionKey` (`SessionKey`) 
) ENGINE=MyISAM DEFAULT CHARSET=utf8"; //新建数据库 sql语句
mysql_query($sql);
echo "成功新建数据库表！";
?>

/////////MysqlSession 类如下：
<?php 
class MysqlSession {
// 注意在有使用Session的页面。页面一定要顶格，页面开始处不能留空。
private $DB_SERVER = "localhost"; // 数据库服务器主机名
 private $DB_NAME = ""; // 数据库名字
 private $DB_USER = "root";  // MYSQL 数据库访问用户名 
 private $DB_PASS = "";  // MYSQL 数据库访问密码 
 private $DB_SELECT_DB = ""; 
//private $SESS_LIFE = 1440;  // Session的最大使用时长，单位秒。
private $SESS_LIFE = 0;
function MysqlSession (&$sessionDB) {
 //session_write_close();
 $this->DB_NAME = &$sessionDB;
 $this->SESS_LIFE = get_cfg_var("session.gc_maxlifetime");
 session_module_name(&#39;user&#39;);
 session_set_save_handler( 
 array(&$this, &#39;sess_open&#39;), 
 array(&$this, &#39;sess_close&#39;), 
 array(&$this, &#39;sess_read&#39;), 
 array(&$this, &#39;sess_write&#39;), 
 array(&$this, &#39;sess_destroy&#39;), 
 array(&$this, &#39;sess_gc&#39;) 
 );
 session_start();
}
function sess_open($save_path, $session_name){ // 打开数据库连接
 if (! $this->DB_SELECT_DB = mysql_pconnect($this->DB_SERVER, $this->DB_USER, $this->DB_PASS)) { 
 echo "SORRY! MYSQL ERROR : Can&#39;t connect to $this->DB_SERVER as $DB_USER"; 
 echo "MySQL Error: ", mysql_error(); 
 die; 
 } 
 if (! mysql_select_db($this->DB_NAME, $this->DB_SELECT_DB)) { 
 echo "SORRY! MYSQL ERROR : Unable to select database $this->DB_NAME"; 
 die; 
 } 
 return true; 
} 
function sess_close() { 
  return true; 
} 
function sess_read($SessionKey){ 
  $Query = "SELECT SessionArray FROM sessions WHERE SessionKey = &#39;".$SessionKey."&#39; AND SessionExpTime > " . time();
  // 过期不读取。
  $Result = mysql_query($Query, $this->DB_SELECT_DB); 
 if (list($SessionArray) = mysql_fetch_row($Result)) { 
   return $SessionArray; 
 } 
 return false; 
} 
function sess_write($SessionKey, $VArray) { 
 $SessionExpTime = time() + $this->SESS_LIFE;
 // 更新Session过期时间，
 //Session过期时间 = 最后一次更新时间 + Session的最大使用时长
 $SessionArray = addslashes($VArray); 
 $Query = "INSERT INTO sessions (SessionKey,SessionExpTime,SessionArray) VALUES (&#39;".$SessionKey."&#39;,&#39;".$SessionExpTime."&#39;,&#39;".$SessionArray."&#39;)"; 
 $Result = mysql_query($Query, $this->DB_SELECT_DB); 
 if (!$Result){ 
   $Query = "UPDATE sessions SET SessionExpTime = &#39;".$SessionExpTime."&#39;, SessionArray = &#39;".$SessionArray."&#39; WHERE SessionKey = &#39;".$SessionKey."&#39; AND SessionExpTime > " . time(); 
   $Result = mysql_query($Query, $this->DB_SELECT_DB); 
 } 
 return $Result; 
} 
function sess_destroy($SessionKey) { 
 $Query = "DELETE FROM sessions WHERE SessionKey = &#39;".$SessionKey."&#39;"; 
 $Result = mysql_query($Query, $this->DB_SELECT_DB); 
 return $Result; 
} 
function sess_gc($maxlifetime) {
// 这个垃圾清除器系统调用。
//默认是1440秒清除一次。参数可以在PHP.ini里面设置。
 $Query = "DELETE FROM sessions WHERE SessionExpTime < " . time(); 
 $Result = mysql_query($Query, $this->DB_SELECT_DB); 
 return mysql_affected_rows($this->DB_SELECT_DB); 
} 
}
?>
//用法：在原来使用 session_start 的地方，替换成 $session = new MysqlSession () 
//注意：包含此程序前要打开数据库，主程序退出前不能关闭数据库，否则会出错。

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