MySQL 数据库 [Err] 1093 - You can't specify target table 'd_alarm' for update in FROM clause
更新数据库时，发生如下错误：
[Err] 1093 - You can't specify target table 'd_alarm' for update in FROM clause
SQL 语句为：
UPDATE d_alarm SET alarmEndTime = '2015-09-11 11:00:24.17' WHERE (select case when measurePointId is null then 0 else measurePointId end as measurePointId from d_alarm) = null AND alarmCode = '29' AND eId = 22
解决方法：
把要更新的几列数据查询出来做为一个第三方表，然后筛选更新。
改为：
UPDATE d_alarm d1 SET d1.alarmEndTime = '2015-09-11 11:00:24.17' WHERE
(select case when d2.measurePointId is null then 0 else d2.measurePointId end as measurePointId from (SELECT * FROM d_alarm) d2) =0 AND alarmCode = '29' AND eId = 22
