Item in two db tables

If I want to find a list of items in one table whose id does not appear in another table, can that be done in one query? I can only figure it out if I use two queries. $result=mysql_query("SELECT id,item FROM table1"); while ($row=mysql_fetch_array($result)) { $thisid=$row["id"]; $thisitem=$row["item"]; $ckresult=mysql_query("SELECT id FROM table2 WHERE id=$thisid"); if (!mysql_num_rows($ckresult)) { echo "$thisitem using id $thisid is in table 1 but does not appear in table 2<BR>"; } // end if } // end while kind regards, bill hollett