<?php
$objConnect = mysql_connect("localhost","root","admin1234") or die("Error Connect to Database");
$objDB = mysql_select_db("itbookonline");
$a1 = isset($_GET['txtKeyword']) ? $_GET['txtKeyword'] : '';
$a2 = isset($_GET['txtKeyword2']) ? $_GET['txtKeyword2'] : '';
$strAction = $a1 AND $a2;
    if($strAction != "")
    {
$strSQL = "SELECT *
          FROM tbl_order_item (ต้องการเพิ่มอีก 2 ตาราง)
          WHERE (od_id BETWEEN $a1 AND $a2)
          ORDER BY od_id DESC";
    }    
$objQuery = mysql_query($strSQL) or die ("Error Query [".$strSQL."]");
?>