Select those those which are absent?

[OhLordy]

Hi I have two tables A and B I want to do a query that returns all rows in A for which there is no coresponding key in table B. It is a 1-1 relationship between the two tables.

Thanks in advance
Rob

[OhLordy]

Hey, Solved it with a left join. Then checked to see if there was anything in the second value.
SELECT A.a as a1, B.a as a2 FROM A LEFT JOIN B on B.a=A.a;
then

<?php
if($row['a2']=="") {
  //do what I need to
} else {
  //do nothing
}
?>