mysql命令列表出现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,在执行时我希望整个事务失败,因此我应该不在myTable中看到values1。 但不幸的是,即使交易有错误,表也被填充了values1。
我有什么想法可以回滚吗? (再次,如果有任何错误)?
编辑 - 从 DDL 更改为标准 SQL
您可以使用13.6.7.2。 DECLARE ... HANDLER 语法按以下方式:
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,请检查以下 SQL Fiddle。
如果您需要在代码中标记特定的 SQL 异常,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 ;
上面的解决方案很好,但让它变得更简单
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 ;