是否可以在存储过程中使用动态SQL创建MySQL触发器？ [英] Can MySQL triggers be created with dynamic SQL from within a stored procedure?

问题描述

是否可以在存储过程中使用动态生成的SQL在MySQL中创建触发器？我正在通过准备一条语句在过程中执行其他动态构造的查询，但是当我尝试使用相同的方法创建触发器时，出现以下错误：

Is it possible to create a trigger in MySQL using dynamically generated SQL from within a stored procedure? I am executing other dynamically constructed queries in my procedure by preparing a statement, but when I try the same approach to create a trigger I get the following error:

错误代码：1295在准备好的语句协议中尚不支持此命令

ERROR Code: 1295This command is not supported in the prepared statement protocol yet

来自 错误＃31625，PREPARED STATEMENT语法不允许创建触发器 自2007年以来一直在抱怨同一件事。

From Bug #31625, PREPARED STATEMENT syntax does not allow to create TRIGGERS I see other people have been complaining about the same thing since 2007.

从 WL＃2871：准备尚未修复的任何SQL 。

有没有解决此问题的方法？还有另一种使用动态SQL创建触发器的方法吗？

Is there a workaround for this problem? Is there another way of creating triggers with dynamic SQL?

基本上，我想做的是动态创建触发器，以记录用于在各种不同表上插入的审计数据。我在* audit_tables *表中列出了要审核的表。

Basically what I am trying to do is dynamically create triggers for recording audit data for inserts on various different tables. I am listing the tables I want to audit in an *audit_tables* table. The stripped-down procedure below iterates over the entries in that table and tries to create the trigger.

drop procedure if exists curtest;
delimiter |
create procedure curtest()
BEGIN
    DECLARE done INT DEFAULT 0;
    declare tn varchar(16);
    declare cur cursor for select table_name from audit_tables;
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;
    OPEN cur;
    read_loop: LOOP
        fetch cur into tn;
        if done then
            leave read_loop;
        end if;

        /* Create the BEFORE INSERT trigger */
        set @sql = concat('CREATE TRIGGER audit_', tn, '_bi BEFORE INSERT ON ', tn, '
            FOR EACH ROW BEGIN
                set new.foo="bar";
            END;');
        PREPARE stmt FROM @sql;
        EXECUTE stmt;
        DEALLOCATE  PREPARE stmt;
    end LOOP;
    close cur;
END;
|
delimiter ;

call curtest();

推荐答案

正如您提到的错误所说，<$ c在准备好的语句中不支持$ c> CREATE TRIGGER 命令。

As the error you mention says, the CREATE TRIGGER command is not supported within prepared statements.

我认为更可行的选择是使用具有MySQL的脚本语言绑定（如PHP）可自动创建触发器。顺便说一句，我只记得MySQL Workbench使用Lua作为这种事情的脚本语言。

I think a more viable option is to use a scripting language that has MySQL bindings, like PHP, to automate the trigger creation. By the way, I just remembered that MySQL Workbench uses Lua as a scripting language for this sort of things.

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