php使用MySQL保存session会话的方法

<?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); 
$sql="SHOW DATABASES LIKE '".$data_name."'"; // 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);
$sql="CREATE TABLE `sessions` ( 
`SessionKey` varchar(32) NOT NULL default '', 
`SessionArray` blob NOT NULL, 
`SessionExpTime` int(20) unsigned NOT NULL default '0', 
PRIMARY KEY (`SessionKey`), 
KEY `SessionKey` (`SessionKey`) 
) ENGINE=MyISAM DEFAULT CHARSET=utf8"; //新建数据库 sql语句
mysql_query($sql);
echo "成功新建数据库表！";
?>

<?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;
  $this->SESS_LIFE = get_cfg_var("session.gc_maxlifetime");
  session_module_name('user');
  session_set_save_handler( 
  array(&$this, 'sess_open'), 
  array(&$this, 'sess_close'), 
  array(&$this, 'sess_read'), 
  array(&$this, 'sess_write'), 
  array(&$this, 'sess_destroy'), 
  array(&$this, 'sess_gc') 
  );
  session_start();
}
function sess_open($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'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){  
    $Query = "SELECT SessionArray FROM sessions WHERE SessionKey = '".$SessionKey."' 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); 
  $Query = "INSERT INTO sessions (SessionKey,SessionExpTime,SessionArray) VALUES ('".$SessionKey."','".$SessionExpTime."','".$SessionArray."')"; 
  $Result = mysql_query($Query, $this->DB_SELECT_DB); 
  if (!$Result){ 
      $Query = "UPDATE sessions SET SessionExpTime = '".$SessionExpTime."', SessionArray = '".$SessionArray."' WHERE SessionKey = '".$SessionKey."' AND  SessionExpTime > " . time(); 
      $Result = mysql_query($Query, $this->DB_SELECT_DB); 
  }  
  return $Result; 
} 
function sess_destroy($SessionKey) { 
  $Query = "DELETE FROM sessions WHERE SessionKey = '".$SessionKey."'"; 
  $Result = mysql_query($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); 
} 
}
?>