problems with looping array

here's the situation. I'm making a shopping cart, when an item is added it's item number is added into an array. I then want this array's items to be compared agains the database. Unfortunately I haven't been able to use a variable in the query string of MySQL. something along the lines of.... <?PHP include ('connect.php'); $result = mysql_query("SELECT * FROM ar LEFT JOIN company on ar.company_id=company.company_id LEFT JOIN scale on ar.scale_id=scale.scale_id WHERE item_number =" . $item[$index]); ?> where $item is the array of item numbers and $index is an auto incrementing number that increments at the end of the loop. Please help if you know of anyway to use this variable. Also, I can post my whole script if needed...I just didn't want unneeded info posted. Thanks in advance. -Jordan