PHP, Mysql-query

Hi everyone! I want to do the following query with php connected to mysql: I have one table with columns named NN , FN and A. Now I want mysql to find (a): all data records where NN = $var (well, that is no problem for me) But now, I want it to get all data records in that table where the whole column of FN with many different results (from the former query, where NN=$var) is present. It is no problem for me to devide that task into two querys and make a script with php. But I want it more effective and faster, of course! Thus I want to put it into one query! To make it more clear, an example: First I get the following result by doing a query that gives me everything where NN=13 NN FN A 13 11 x 13 56 y 13 34 z 13 10 a Now I want it to find all records where FN =11, FN=56, FN=34, FN=10. Would be very happy for response! André