Set operators combine the results of two component queries into a single result. Queries containing set operators are called compound queries. Table 4-4 lists SQL set operators. They are fully described, including examples and restrictions on these operators, in "The UNION [ALL], INTERSECT, MINUS Operators".
Table 4-4 Set Operators
All distinct rows selected by either query
All rows selected by either query, including all duplicates
All distinct rows selected by both queries
All distinct rows selected by the first query but not the second