parenthesized_query_expression:
    ( query_expression [order_by_clause] [limit_clause] )
      [order_by_clause]
      [limit_clause]
      [into_clause]

query_expression:
    query_block [set_op query_block [set_op query_block ...]]
      [order_by_clause]
      [limit_clause]
      [into_clause]

query_block:
    SELECT ... | TABLE | VALUES

order_by_clause:
    ORDER BY as for SELECT

limit_clause:
    LIMIT as for SELECT

into_clause:
    INTO as for SELECT

set_op:
    UNION | INTERSECT | EXCEPT

MySQL 9.0 根據上述語法支援以括號括起來的查詢表達式。最簡單的情況下，以括號括起來的查詢表達式包含單個 SELECT 或其他返回結果集的敘述，並且沒有後續的可選子句。

(SELECT 1);
(SELECT * FROM INFORMATION_SCHEMA.SCHEMATA WHERE SCHEMA_NAME = 'mysql');

TABLE t;

VALUES ROW(2, 3, 4), ROW(1, -2, 3);

以括號括起來的查詢表達式也可以包含由一個或多個集合運算符（例如 UNION）連結的查詢，並以任何或全部可選子句結尾。

mysql> (SELECT 1 AS result UNION SELECT 2);
+--------+
| result |
+--------+
|      1 |
|      2 |
+--------+
mysql> (SELECT 1 AS result UNION SELECT 2) LIMIT 1;
+--------+
| result |
+--------+
|      1 |
+--------+
mysql> (SELECT 1 AS result UNION SELECT 2) LIMIT 1 OFFSET 1;
+--------+
| result |
+--------+
|      2 |
+--------+
mysql> (SELECT 1 AS result UNION SELECT 2)
       ORDER BY result DESC LIMIT 1;
+--------+
| result |
+--------+
|      2 |
+--------+
mysql> (SELECT 1 AS result UNION SELECT 2)
       ORDER BY result DESC LIMIT 1 OFFSET 1;
+--------+
| result |
+--------+
|      1 |
+--------+
mysql> (SELECT 1 AS result UNION SELECT 3 UNION SELECT 2)
       ORDER BY result LIMIT 1 OFFSET 1 INTO @var;
mysql> SELECT @var;
+------+
| @var |
+------+
|    2 |
+------+

INTERSECT 的運算優先於 UNION 和 EXCEPT，因此以下兩個敘述是等效的。

SELECT a FROM t1 EXCEPT SELECT b FROM t2 INTERSECT SELECT c FROM t3;

SELECT a FROM t1 EXCEPT (SELECT b FROM t2 INTERSECT SELECT c FROM t3);

以括號括起來的查詢表達式也用作查詢表達式，因此查詢表達式（通常由查詢區塊組成）也可能包含以括號括起來的查詢表達式。

(TABLE t1 ORDER BY a) UNION (TABLE t2 ORDER BY b) ORDER BY z;

查詢區塊可以有尾隨的 ORDER BY 和 LIMIT 子句，它們會在外部集合運算、ORDER BY 和 LIMIT 之前被應用。

您不能在沒有用括號括住查詢區塊的情況下使其具有尾隨的 ORDER BY 或 LIMIT，但括號可以用於以各種方式強制執行。

本節中描述的語法受某些限制約束。