GaussDB-DEALLOCATE

GaussDB-DEALLOCATE

功能描述

DEALLOCATE用于删除预备语句。

注意事项

• 如果用户没有明确删除一个预备语句，那么它将在会话结束的时候被删除。
• 语法中PREPARE关键字总会被忽略。

语法格式

| ``` DEALLOCATE [ PREPARE ] { name | ALL };

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![](https://p6-xtjj-sign.byteimg.com/tos-cn-i-73owjymdk6/1224c333797448cd9e74ca9a3136cbf4~tplv-73owjymdk6-jj-mark-v1:0:0:0:0:5o6Y6YeR5oqA5pyv56S-5Yy6IEAgamVycnl3YW5nMTk4Mw==:q75.awebp?rk3s=f64ab15b&x-expires=1772696937&x-signature=EytvZH8uOqV4DAEOaXC1G4ubWfI%3D)

#### 参数说明

-   **name**

    将要删除的预备语句。

-   **ALL**

    删除所有预备语句。

#### 示例

| ```
--查看现有预备语句。 gaussdb=# SELECT name, statement, parameter_types FROM pg_prepared_statements;  name | statement | parameter_types  ------+-----------+----------------- (0 rows)  --创建q1,q2,q3，q4四个预备语句。 gaussdb=# PREPARE q1 AS SELECT 1 AS a; PREPARE gaussdb=# PREPARE q2 AS SELECT 1 AS a; PREPARE gaussdb=# PREPARE q3 AS SELECT 1 AS a; PREPARE gaussdb=# PREPARE q4 AS SELECT 1 AS a; PREPARE  --再次查看现有预备语句。 gaussdb=# SELECT name, statement, parameter_types FROM pg_prepared_statements;  name |          statement           | parameter_types  ------+------------------------------+-----------------  q1   | PREPARE q1 AS SELECT 1 AS a; | {}  q4   | PREPARE q4 AS SELECT 1 AS a; | {}  q3   | PREPARE q3 AS SELECT 1 AS a; | {}  q2   | PREPARE q2 AS SELECT 1 AS a; | {} (4 rows)  --删除q4预备语句并查看剩余预备语句。 gaussdb=# DEALLOCATE q4; gaussdb=# SELECT name, statement, parameter_types FROM pg_prepared_statements;  name |          statement           | parameter_types  ------+------------------------------+-----------------  q1   | PREPARE q1 AS SELECT 1 AS a; | {}  q3   | PREPARE q3 AS SELECT 1 AS a; | {}  q2   | PREPARE q2 AS SELECT 1 AS a; | {} (3 rows）  --删除所有预备语句并查看剩余预备语句。 gaussdb=# DEALLOCATE ALL; DEALLOCATE ALL gaussdb=# SELECT name, statement, parameter_types FROM pg_prepared_statements;  name | statement | parameter_types  ------+-----------+----------------- (0 rows) 
``` |
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