Question

伙计们我试图使用嵌套查询从数据库中删除一些记录：

delete from imageviewer_crreviewerformdata
where imageviewer_crreviewerformdata.FormDataId in
(select distinct imageviewer_crreviewerformdata.FormDataId
from imageviewer_crreviewerformdata,imageviewer_crtask
where imageviewer_crreviewerformdata.TaskId = imageviewer_crtask.TaskId
and imageviewer_crtask.RevProtId in (1));

我得到了众所周知的mysql异常。有人可以帮助制定查询吗？

Answer 1

delete d 
from imageviewer_crreviewerformdata d
inner join imageviewer_crtask t on d.TaskId = t.TaskId
where t.RevProtId in (1)

Answer 2

我认为它只是告诉你从查询中删除表别名

delete from imageviewer_crreviewerformdata
where FormDataId in
(select distinct imageviewer_crreviewerformdata.FormDataId
from imageviewer_crreviewerformdata,imageviewer_crtask
where imageviewer_crreviewerformdata.TaskId = imageviewer_crtask.TaskId
and imageviewer_crtask.RevProtId in (1));

Answer 3

当我需要使用该表作为select的源从表中删除时，我通常创建一个临时表作为删除的参考。也许它有点传统，但它的确有效。

您需要创建一个临时表，通过连接临时表来删除，然后删除临时表。

CREATE TEMPORARY TABLE temp.tempdelete AS select distinct
imageviewer_crreviewerformdata.FormDataId
from imageviewer_crreviewerformdata,imageviewer_crtask
where imageviewer_crreviewerformdata.TaskId = imageviewer_crtask.TaskId
and imageviewer_crtask.RevProtId in (1));

然后你可以删除

DELETE FROM imageviewer_crreviewerformdata WHERE FormDataId IN (SELECT FormDataId FROM temp.tempdelete)

然后放下临时表。

DROP TABLE temp.temptable.

这要求您有一个名为temp的文件夹。它也是一个很好的解决方案，可以在存储过程中更容易使用。

MySQL on delete错误 - 无法在FROM子句中指定更新目标表

3 个答案: