Important
Self-managed SingleStore will soon transition from version 9.1 RC to version 10. This new semantic versioning scheme will provide SingleStore with finer control over engine and feature releases that were not possible with the current versioning scheme.
In the interim, SingleStore 9.1 RC can be used to preview, evaluate, and provide feedback on the new and upcoming features in SingleStore 10 prior to its general availability. Ahead of this transition, SingleStore 9.0 is recommended for production workloads, which can later be upgraded to SingleStore 10.
UNION
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The UNION command 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
SELECTstatements must select the same number of columns. -
UNIONstatements are converted into nested sub-select queries by the query processor. -
The maximum depth of nested sub-select queries is 40.
Beyond this the UNIONstatements are converted toTABLE, allowing you to write up to 337 statements (0-336).
Examples
SELECT * FROM table_a UNION ALL SELECT * FROM table_b;SELECT * FROM table_a UNION SELECT * FROM table_b;
SELECT * FROM id_t UNION ALL SELECT * FROM id_t2;
+------+----------------------------------------------------------------------------+
| a | b |
+------+----------------------------------------------------------------------------+
| 1 | 0xE82C75FA86974BE7903270F4353D865C |
| 1 | 0x31343865306665352D666666322D346363362D383634622D313838303637313135653236 |
+------+----------------------------------------------------------------------------+Last modified: