A set operator merges two query results into one result. The queries that contain set operators are compound queries.
| Operator | Return value |
|---|---|
| UNION | Returns all the distinct rows that are selected by a query. |
| UNION ALL | Returns all the rows that are selected by a query. The return result includes all the duplicates. |
| INTERSECT | Returns all the distinct rows that are selected by both queries. |
| MINUS | Returns all the distinct rows that are selected by the first query. The return result excludes the rows that are included in the result of the second query. |
For more information and examples about the set operators, see the descriptions of the UNION ALL, INTERSECT, and MINUS operators in the Queries and subqueries topic.