Combine results, not columns

A customer may belong to several lists: Haifa residents, business customers or buyers. Set operators merge, intersect or subtract results of the same shape. Decide explicitly whether repetitions remain.

UNION merges without duplicates; UNION ALL keeps them; INTERSECT keeps common rows; EXCEPT subtracts the second result from the first.

Combine results, not columns: UNION merges without duplicates; UNION ALL keeps them; INTERSECT keeps common rows; EXCEPT subtracts the second result from the first.