How to operate MySQL database and session dialogue in PHP

//////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。