通过唯一索引S锁与X锁来了解MySQL死锁套路

# 构造数据
CREATE TABLE `t1` (
 `id` int(11) NOT NULL AUTO_INCREMENT,
 `name` varchar(10),
 `level` int(11),
 PRIMARY KEY (`id`),
 UNIQUE KEY `uk_name` (`name`)
);
INSERT INTO `t1` (`name`, `level`) VALUES ('A',0);

# 出现问题的sql语句如下，并发情况下就会出现死锁
INSERT ignore INTO `t1` (`name`, `level`) VALUES ('A',0);
update t1 set level = 1 where name = "A";