[Err] 1205 - Lock wait timeout exceeded; try restarting transaction

简单说，就是现在要对一条记录进行修改，那么sql语句应该是这样的：

update user set uname = 'zhangsan' where uid = 1

如果执行这条sql语句，发现一直处于处理中的状态，然后等一定时间（超时）后报错[Err] 1205 - Lock wait timeout exceeded; try restarting transaction 。

说明 uid = 1 的这条记录正处于一个未结束的事务中。

MySQL - 锁等待超时与information_schema的三个表：
-- 1.information_schema.innodb_trx–当前运行的所有事务
select * from information_schema.innodb_trx;

-- information_schema.innodb_locks–当前出现的锁
select * from information_schema.innodb_locks;

-- information_schema.innodb_lock_waits–锁等待的对应关系
select * from information_schema.innodb_lock_waits;
--------------------------------------------------------------
select concat('kill',' ',trx_mysql_thread_id,';') from information_schema.innodb_trx