删除 SQL 查询结果集

本文介绍了删除 SQL 查询结果集的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我正在尝试删除 SQL 结果集，但它不起作用:

I'm trying to delete an SQL result set but it won't work:

DELETE FROM votes WHERE id IN ( SELECT * FROM votes v LEFT JOIN comments c ON f.id = v.post_id GROUP BY v.id HAVING COUNT(cment) = 0 )

推荐答案

确实，您不能在直接子选择中使用要从中删除行的同一个表，但有一个小技巧 - 在子选择上一个子选择作为派生表 - 你可以做到:

It's true, that you can't use the same table from which you want to delete rows in a direct subselect, but with a little trick - a subselect on a subselect as derived table - you can do it:

DELETE FROM votes WHERE id IN ( SELECT t.id FROM ( SELECT v.id, COUNT(cment) cnt FROM votes v LEFT JOIN comments c ON f.id = v.post_id GROUP BY v.id HAVING COUNT(cment) = 0 ) t );

我假设应该删除没有注释的行.

I'm assuming that the rows without comments should be deleted.