Aselect user.* from A left outer join B on A.id=B.id where B.id is null
Bselect user.* from A join B on A.id=B.id where B.id is null
Cselect user.* from A right outer join B on A.id=B.id where B.id is null
Dselect user.* from A inner join B on A.id=B.id where B.id is null