php实现留言板功能（代码详解）

<?php
session_start();
$uid = $_SESSION["zhang"];
include("../db.class.php");
$db = new db();
$jsr = $_POST["shou"];
$neirong = $_POST["lynr"];
$sj = date("Y-m-d H:i:s");
$sql = "insert into liuyan values('','{$uid}','{$jsr}','{$sj}','{$neirong}',0)";
if($db->Query($sql,0))
{
 header("location:zym.php");
}
else
{
 echo "发布失败！";
}