sql-statement-deallocate.md

title	summary	aliases
DEALLOCATE	TiDB 数据库中 DEALLOCATE 的使用概况。	/docs-cn/dev/sql-statements/sql-statement-deallocate/ /docs-cn/dev/reference/sql/statements/deallocate/

DEALLOCATE

DEALLOCATE 语句用于为服务器端预处理语句提供 SQL 接口。

语法图

DeallocateStmt ::=
    DeallocateSym 'PREPARE' Identifier

DeallocateSym ::=
    'DEALLOCATE'
|   'DROP'

Identifier ::=
    identifier
|   UnReservedKeyword
|   NotKeywordToken
|   TiDBKeyword

示例

{{< copyable "sql" >}}

PREPARE mystmt FROM 'SELECT ? as num FROM DUAL';

Query OK, 0 rows affected (0.00 sec)

{{< copyable "sql" >}}

SET @number = 5;

Query OK, 0 rows affected (0.00 sec)

{{< copyable "sql" >}}

EXECUTE mystmt USING @number;

+------+
| num  |
+------+
| 5    |
+------+
1 row in set (0.00 sec)

{{< copyable "sql" >}}

DEALLOCATE PREPARE mystmt;

Query OK, 0 rows affected (0.00 sec)

MySQL 兼容性

DEALLOCATE 语句与 MySQL 完全兼容。如发现任何兼容性差异，请在 GitHub 上提交 issue。

另请参阅

• PREPARE
• EXECUTE