//get rid of all kinds of spaces $IDs = preg_replace(‘/s+/’, ”, $inputIDs); if(!preg_match(”/^\d+$|^(\d+,)+\d+$/”, $IDs)) { echo “Invalid Input”; } You could use the validated IDs above in a SQL like the this: SELECT * FROM t1 WHERE id IN($IDs) Disclaimer: I am not going to be responsible for any kind of SQL injection resulting from…