set autocommit=0指事务非自动提交，自此句执行以后，每个SQL语句或者语句块所在的事务都需要显示"commit"才能提交事务。
1、不管autocommit 是1还是0
START TRANSACTION 后，只有当commit数据才会生效，ROLLBACK后就会回滚。
2、当autocommit 为 0 时
不管有没有START TRANSACTION。
只有当commit数据才会生效，ROLLBACK后就会回滚。
3、如果autocommit 为1 ，并且没有START TRANSACTION 。
调用ROLLBACK是没有用的。即便设置了SAVEPOINT。
回滚成功
set autocommit =1;
DELIMITER $$
DROP PROCEDURE IF EXISTS mmmm $$
CREATE DEFINER=`tms_admin`@`%` PROCEDURE `mmmm`()
BEGIN
DECLARE t_error INTEGER DEFAULT 0;
DECLARE CONTINUE HANDLER FOR SQLEXCEPTION,SQLWARNING,NOT FOUND SET t_error=1;
START TRANSACTION;
SAVEPOINT p1;
update t_user set instance_seq_id = ‘tt00006‘;
update t_user set instance_seq_id000 = ‘tt00007‘;
IF t_error = 1 THEN
ROLLBACK to p1;
ELSE
COMMIT;
END IF;
END$$
DELIMITER ;
CALL `tms_inst_tt00003`.`mmmm`();
set autocommit =0;
DELIMITER $$
DROP PROCEDURE IF EXISTS mmmm $$
CREATE DEFINER=`tms_admin`@`%` PROCEDURE `mmmm`()
BEGIN
DECLARE t_error INTEGER DEFAULT 0;
DECLARE CONTINUE HANDLER FOR SQLEXCEPTION,SQLWARNING,NOT FOUND SET t_error=1;
START TRANSACTION;
SAVEPOINT p1;
update t_user set instance_seq_id = ‘tt00006‘;
update t_user set instance_seq_id000 = ‘tt00007‘;
IF t_error = 1 THEN
ROLLBACK to p1;
ELSE
COMMIT;
END IF;
END$$
DELIMITER ;
CALL `tms_inst_tt00003`.`mmmm`();
回滚成功
set autocommit =0;
DELIMITER $$
DROP PROCEDURE IF EXISTS mmmm $$
CREATE DEFINER=`tms_admin`@`%` PROCEDURE `mmmm`()
BEGIN
DECLARE t_error INTEGER DEFAULT 0;
DECLARE CONTINUE HANDLER FOR SQLEXCEPTION,SQLWARNING,NOT FOUND SET t_error=1;
SAVEPOINT p1;
update t_user set instance_seq_id = ‘tt00006‘;
update t_user set instance_seq_id000 = ‘tt00007‘;
IF t_error = 1 THEN
ROLLBACK to p1;
ELSE
COMMIT;
END IF;
END$$
DELIMITER ;
回滚成功
mysql中set autocommit=0与start transaction区别
原文：https://www.cnblogs.com/kenshinobiy/p/9584110.html