UNION
Combines results from multiple SELECT statements. UNION DISTINCT
removes duplicate rows, while UNION ALL
does not remove them. UNION
is equivalent to UNION DISTINCT
.
Syntax
SELECT ... UNION [ALL | DISTINCT] SELECT ... [UNION [ALL | DISTINCT] SELECT ...]
Remarks
The first and all subsequent
SELECT
statements must select the same number of columns.
Examples
SELECT * FROM table_a UNION ALL SELECT * FROM table_b; SELECT * FROM table_a UNION SELECT * FROM table_b;