session入mysql

<?php
/**
 * Created by PhpStorm.
 * User: user
 * Date: 2016/11/3 0003
 * Time: 下午 8:12
 */
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(){
    @$link = mysql_connect('127.0.0.1', 'root', 'root');
    mysql_query('set names utf8');
    mysql_query('use cms');
}
function close(){
    mysql_close();
}
function read($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){
    // 讲session存入数据库
    $read = mysql_query("select * from session where session_data='{$sess_data}'");
    $info = mysql_fetch_assoc($read);
//    var_dump($info);die;
    if (empty($info)) {
        $sql1="delete from session where session_data != '{$sess_data}'";
        mysql_query($sql1);
        $time = time();
        mysql_query("insert into session (session_id, session_data, session_time) values ('{$sess_id}', '{$sess_data}', '{$time}')");
    } else {
        $sql1="delete from session where session_data != '{$sess_data}'";
        mysql_query($sql1);
        $sql = "update session set session_id='{$sess_id}',session_time=now() where session_data='{$sess_data}'";
        mysql_query($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);
}

if (!empty($_POST['name'])) {
    $name = $_POST['name'];
    session_start();
    $_SESSION['name'] = "$name";
}