Wenn Du auf Release 6.1 oder höher bist:

Code:
Select  a.*, b.*
From FileA a Full Outer Join FileB b
   on a.key1 = b.Key1
     and a.Key2 = b.Key2
     and ....
     and a.KeyN = b.KeyN
vor 6.1

Code:
   Select a.*, b.*
   From FileA a Left Outer Join FileB b on a.Key1 = b.Key1 ....
Union
   Select a.*, b.*
   From FileA a Right Outer Join FileB b. on a.Key1 = b.Key1 ....;