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

memsql> SELECT * FROM table_a UNION ALL SELECT * FROM table_b;
memsql> SELECT * FROM table_a UNION SELECT * FROM table_b;

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