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");    
    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["name"]="aa";    
//echo session_id();    
echo $_SESSION["name"];