Hvad med sådan noget?
SELECT A, B FROM Table1 EXCEPT SELECT A,B FROM Table2
UNION
SELECT A, B FROM Table2 EXCEPT SELECT A,B FROM Table1
Her er et eksempel med FULL OUTER JOIN-metoden (forudsat at A ikke er nullbar i begge tabeller)
SELECT IsNull(Table1.A, Table2.A) a,IsNull(Table1.B, Table2.B) B
FROM Table1
FULL OUTER JOIN Table2 ON (Table1.A=Table2.A AND Table1.B=Table2.B)
WHERE Table1.A is null or Table2.A is null