Merge Tables

I have a very simple question which is anoying me already for a very long time. I have two tables both with a key field, a common field and a table specic field. Like :

Key,common,spec1
222,AAAA,20000
333,BBBB,0000
444,CCCC,22000

Key,common,spec2
111,EEEE,PRO
222,AAAA,PRV
777,FFFF,PSR

Which I want to merge to one table like this :

Key,common,spec1,spec2
111,EEEE,-----,PRO
222,AAAA,20000,PRV
333,BBBB,10000,---
444,CCCC,22000,---
777,EEEE,----- ,PSR

If I set a relation on the keyfield, where both keys should be equal, the result is :

222,AAAA,20000,PRV

If I set a relation on the keyfield, wiith all records from table 1 and from table 2 where both keys are equal, the result is :

222,AAAA,20000,PRV
333,BBBB,10000,---
444,CCCC,22000,---

If I set a relation on the keyfield, with all records from table 2 and from table 1 where both keys are equal, the result is :

111,EEEE,-----,PRO
222,AAAA,20000,PRV
777,EEEE,----- ,PSR

How do I solve this?