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  1. MariaDB Server
  2. MDEV-19956

Queries with subqueries containing UNION are not parsed

    Details

    • Type: Bug
    • Status: Closed (View Workflow)
    • Priority: Critical
    • Resolution: Fixed
    • Affects Version/s: 10.4
    • Fix Version/s: 10.4.9, 10.5.0
    • Component/s: Parser
    • Labels:
      None

      Description

      The following query

      SELECT ((SELECT a FROM t1 LIMIT 2) UNION (SELECT a FROM t2 LIMIT 2) LIMIT 1) AS r FROM t1 AS t;
      

      returns syntax error message in 10.4:

      ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'UNION (SELECT a FROM t2 LIMIT 2) LIMIT 1) AS r FROM t1 AS t' at line 1
      

      Reprodicible in with the following test case

      CREATE TABLE t1 (a int);
      INSERT INTO t1 VALUES(1),(2),(3),(4);
      CREATE TABLE t2 (a int);
      INSERT INTO t2 VALUES (4),(5),(6),(7);
      SELECT ((SELECT a FROM t1 LIMIT 2) UNION (SELECT a FROM t2 LIMIT 2) LIMIT 1) AS r FROM t1 AS t;
      

      10.3 and probably all prior versions return the same error message.
      MySQL-8.0 returns a proper result:

      mysql> SELECT ((SELECT a FROM t1 LIMIT 2) UNION (SELECT a FROM t2 LIMIT 2) LIMIT 1) AS r FROM t1 AS t;
      +------+
      | r    |
      +------+
      |    1 |
      |    1 |
      |    1 |
      |    1 |
      +------+
      

      This query with a subquery in the WHERE clause also failed to be parsed:

      MariaDB [test]> SELECT * FROM t1 WHERE t1.a IN ((SELECT a FROM t1) UNION (SELECT a FROM t2));
      ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'UNION (SELECT a FROM t2))' at line 1
      

      10.3 returns the same error message.

      MySQL-8.0 is ok with the above query:

      mysql> SELECT * FROM t1 WHERE t1.a IN ((SELECT a FROM t1) UNION (SELECT a FROM t2));
      +------+
      | a    |
      +------+
      |    1 |
      |    2 |
      |    3 |
      |    4 |
      +------+
      

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              • Assignee:
                igor Igor Babaev
                Reporter:
                igor Igor Babaev
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                Dates

                • Created:
                  Updated:
                  Resolved: