Question

I have table A with fields user1 and user2 and table B with user3 and user4 pairs.

I want to be able to find any rows from table A where the user1/user2 combination is also in table B.

The order doesn’t matter. For example table A with user1=Mike, user2=Joe would match table B with user3=Joe and user4=Mike.

Answer 1

select a.user1, a.user2 from a, b 
where (a.user1 == b.user3 and a.user2 == b.user4)
or (a.user1 = b.user4 and a.user2 = b.user3);