You can't specify target table '表名' for update in FROM clause”解决方法

You can't specify target table '表名' for update in FROM clause

翻译为：不能先select出同一表中的某些值，再update这个表。

错误语句：

update w_workitems ww set ww.endTime = ww.createTime where ww.gid in(
select * from a_travel a ,w_workitems b where a.instance_id = b.instanceId and a.apply_status = '2'
and a.id>'202001' and b.endTime is null ORDER BY b.createTime desc;

修改后：

UPDATE w_workitems ww
SET ww.endTime = ww.createTime
WHERE
ww.gid IN (
SELECT
aa.gid
FROM
(
SELECT
b.*
FROM
a_travel a,
w_workitems b
WHERE
a.instance_id = b.instanceId
AND a.apply_status = '2'
AND a.id > '202001'
AND b.endTime IS NULL
ORDER BY
b.createTime DESC
) aa
);