Question

如果在mysql命令列表中发生错误，是否可以自动回滚？

例如：

begin transaction;

insert into myTable values1 ...
insert into myTable values2 ...;  -- will throw an error

commit;

现在，执行时我希望整个交易失败，因此我应该不看myTable中的values1。但遗憾的是，即使交易有错误，该表也会被值1限制。

我是如何让它回滚的？（再次，任何错误）？

编辑 - 从DDL更改为标准SQL

Answer 1

您可以通过以下方式使用13.6.7.2. DECLARE ... HANDLER Syntax：

DELIMITER $$

CREATE PROCEDURE `sp_fail`()
BEGIN
    DECLARE `_rollback` BOOL DEFAULT 0;
    DECLARE CONTINUE HANDLER FOR SQLEXCEPTION SET `_rollback` = 1;
    START TRANSACTION;
    INSERT INTO `tablea` (`date`) VALUES (NOW());
    INSERT INTO `tableb` (`date`) VALUES (NOW());
    INSERT INTO `tablec` (`date`) VALUES (NOW()); -- FAIL
    IF `_rollback` THEN
        ROLLBACK;
    ELSE
        COMMIT;
    END IF;
END$$

DELIMITER ;

有关完整示例，请查看以下SQL Fiddle。

Answer 2

如果您需要在代码中使用SIGNAL特定的SQL EXCEPTION，则可以使用EXIT HANDLER。例如：

DELIMITER $$

CREATE PROCEDURE `sp_fail`()
BEGIN
    DECLARE EXIT HANDLER FOR SQLEXCEPTION
    BEGIN
        ROLLBACK;  -- rollback any changes made in the transaction
        RESIGNAL;  -- raise again the sql exception to the caller
    END;

    START TRANSACTION;
    insert into myTable values1 ...
    IF fail_condition_meet THEN
        SIGNAL SQLSTATE '45000' SET MESSAGE_TEXT = 'Custom error detected.', MYSQL_ERRNO = 2000;
    END IF;
    insert into myTable values2 ...  -- this will not be executed
    COMMIT; -- this will not be executed
END$$

DELIMITER ;

Answer 3

上面的解决方案很好，但是使其更简单

DELIMITER $$

CREATE PROCEDURE `sp_fail`()
BEGIN
    DECLARE EXIT HANDLER FOR SQLEXCEPTION
    BEGIN
        ROLLBACK;  -- rollback any error in the transaction
    END;

    START TRANSACTION;
    insert into myTable values1 ...
    insert into myTable values2 ...  -- Fails
    COMMIT; -- this will not be executed
END$$

DELIMITER ;

mysql事务 - 回滚任何异常

3 个答案: