mysql - 在 "INSERT ON"子句中使用用户变量

Question

我尝试使用用户定义的变量创建一个干净的触发器，所以这是我的代码:

---

SET @target_bdd = 'trigger_second';
SET @trigger_name = 'account_copy';
SET @table_name = 'account';
SET @primary_key = 'id';

DROP TRIGGER IF EXISTS `@trigger_name`;

DELIMITER $$

CREATE TRIGGER `@trigger_name` AFTER INSERT
    ON `@table_name`
FOR EACH ROW BEGIN
    INSERT INTO `@target_bdd`.`@table_name`
    SELECT * FROM `@table_name` 
    WHERE `@primary_key` = NEW.`@primary_key`; 
END $$
DELIMITER ;

---

但是我有这个错误:

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that 
corresponds >to your MySQL server version for the right syntax to use near '@table_name
FOR EACH ROW BEGIN INSERT INTO `@target_bdd`.`@table_name` SELECT * ' at line 2

为什么？我试过用其他引号 ('") 但有同样的错误:(

没有引号:

ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '@trigger_name AFTER INSERT ON @table_name FOR EACH ROW BEGIN INSERT INTO @target' at line 1

我尝试使用如下 SQL 指令声明一个用户定义的变量:

SET @sql = CONCAT(
    'CREATE TRIGGER ',
    @trigger_name,
    ' AFTER INSERT ON ',
    @table_name,
    ' FOR EACH ROW BEGIN INSERT INTO ',
    @target_bdd,
    '.',
    @table_name,
    ' SELECT * FROM ',
    @table_name, 
    ' WHERE ',
    @primary_key,
    ' = NEW.',
    @primary_key, 
    '; END'
    );

PREPARE stmt FROM @sql;
EXECUTE stmt;

但我有错误 1295 ( See in MySQL Documentation )

Answer 1

您不能在纯 SQL 中将用户变量用于表名、列等。您也不能在准备好的语句中创建触发器(就像错误告诉您的那样)。似乎目前没有办法做你想做的事。