ติดโค้ดอัพเดท 2 ตาราง แต่ข้อมูลไม่ยอมเปลี่ยน รบกวนช่วยดูโค้ดให้หน่อยนะคะ

<?php
session_start();
 include("db/connect.php");//เรียกใช้ไฟล์connect.php
error_reporting (E_ALL ^ E_NOTICE); //ดัก noticeออกไป
if($_POST["Save"]){
			$contract_id=$_POST["contract_id"];
			$contract_num=$_POST["contract_num"];
	 		$date_con_up=$_POST["date_con_up"];
			$contract_name=$_POST["contract_name"];
			$contract_file=$_POST["contract_file"];
			$date_app_up=$_POST["date_app_up"];
			$append_name=$_POST["append_name"];
			$append_file=$_POST["append_file"];
			$con_description=$_POST["con_description"];
			$p_id=$_POST["p_id"];
			$sid=$_POST["sid"];
			
		
		$sql =   "UPDATE contract  ,append  SET p_id='$p_id',contract_num='$contract_num', 
date_con_up='$date_con_up',contract_name='$contract_name', contract_file='$contract_file',date_app_up='$date_app_up', append_name='$append_name',append_file='$append_file', con_description='$con_description' WHERE contract_num='$sid'    ";

			$query = mysql_query($sql);
			echo "<script type='text/javascript'>alert('บันทึกข้อมูลเรียบร้อยแล้ว')</script>";
   			echo "<meta http-equiv ='refresh'content='0;URL=show_contract.php'>";
}
if($_GET['do']=="edit") //เป็นการคำสั่งในแก้ไขข้อมูล
{
	$sid = $_GET['sid'];
	//echo $sid;
	$sql = "SELECT contract.contract_id,contract.p_id,contract.contract_num ,contract.date_con_up,contract.contract_name ,contract.contract_file, append.date_app_up,append.append_name,append.append_file,contract.con_description
FROM contract
LEFT JOIN append ON contract .contract_id= append.contract_id
WHERE contract_num='$sid' 
ORDER BY contract.contract_id";
	$a = mysql_query($sql)  or die (mysql_error()); 
 	$objResult = mysql_fetch_array($a);
}
?>