删除重复行(不要删除所有重复行) [英] Delete duplicate rows (don't delete all duplicate)

问题描述

我正在使用 postgres.我想删除重复的行.条件是，不会删除重复行集中的 1 个副本.

I am using postgres. I want to delete Duplicate rows. The condition is that , 1 copy from the set of duplicate rows would not be deleted.

即:如果有 5 条重复记录，则将删除其中的 4 条.

i.e : if there are 5 duplicate records then 4 of them will be deleted.

推荐答案

尝试本文中描述的步骤:从 PostgreSQL 数据库中删除重复项.

Try the steps described in this article: Removing duplicates from a PostgreSQL database.

它描述了一种情况，当您必须处理无法分组的大量数据时.

It describes a situation when you have to deal with huge amount of data which isn't possible to group by.

一个简单的解决方案是:

A simple solution would be this:

DELETE FROM foo
       WHERE id NOT IN (SELECT min(id) --or max(id)
                        FROM foo
                        GROUP BY hash)

其中 hash 是重复的东西.

Where hash is something that gets duplicated.

这篇关于删除重复行(不要删除所有重复行)的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！