session入mysql

<?php
ini_set("session.save_handler","user");  
//session.gc_probability = 1 分子  
ini_set("session.gc_probability",1);  
//session.gc_divisor = 1000 分母  
ini_set("session.gc_divisor",2);  
//session.gc_maxlifetime = 1440 垃圾回收时间，session有效期  
session_set_save_handler( "open","close","read","write","destroy","gc" );
//连接数据库  
function open(){  
    @$link = mysql_connect('127.0.0.1', 'root', 'root');  
    mysql_query('set names utf8');  
    mysql_query('use wangbin');  
}  
function close(){  
    mysql_close();  
}  
function read($sess_id){  
    $sql = "select session_data from `session` where session_id = '$sess_id'";  
    $result = mysql_query($sql);  
    if($rows = mysql_fetch_assoc($result)){
        return $rows['session_data']; }
    else{
        return '';
    }  
}  
function write($sess_id,$sess_data){  
    $sql = "insert into `session` (session_id,session_data,session_time) values('$sess_id','$sess_data', now()) on duplicate key update session_data = '$sess_data' , session_time = now()";  //这是为了gc()  
    return mysql_query($sql);  
  
}  
function destroy($sess_id){  
    echo __FUNCTION__;  
    $sql = "delete from `session` where session_id = '$sess_id'";  
    return mysql_query($sql);  
  
}  
function gc($sess_id){  
	$maxlifetime = ini_set("session.gc_maxlifetime",1200);  
    echo __FUNCTION__;  
    $sql = "delete from `session` where now()-session_time > '$maxlifetime' ";  
    return mysql_query($sql);  
}  
header("content-type:text/html;charset=utf8");  
session_start();  
$_SESSION['dname']='aa';  
//echo session_id();  
echo $_SESSION['name'];