Django查询：按列表获取所有不同值的最后一个条目 [英] Django query: get the last entries of all distinct values by list

问题描述

我正在尝试进行Django查询，以从 MySQL 数据库获取每个不同值的最后一个条目的列表。我将在下面显示一个示例，因为这种解释可能非常复杂。使用 .values（）显然可以在Django中单独获取不同的值。我当时在考虑创建几个Django查询，但这看起来很麻烦。有没有简便的方法。

I am trying to make a Django query for getting a list of the last entries for each distinct values from a MySQL database. I will show an example below as this explanation can be very complicated. Getting the distinct values by themselves obviously in Django is no problem using .values(). I was thinking to create couple of Django queries but that looks to be cumbersome. Is there an easy way of doing this.

对于下面的示例。假设我想要具有不同名称的行以及它们的最后一个条目（最新日期）。

For the example below. Suppose I want the rows with distinct Names with their last entry(latest date).

Name            email                 date
_________________________________________________

Dane            [e-mail]        2017-06-20
Kim             [e-mail]         2017-06-10
Hong            [e-mail]        2016-06-25
Dane            [e-mail]        2017-06-04
Susan           [e-mail]       2017-05-21
Dane            [e-mail]        2017-02-01
Susan           [e-mail]         2017-05-20

所有不同的值是Dane，kim，Hong和Susan。我还希望这些最新名称与这些唯一名称相关联的行。我想要的条目列表是下面的行。通知名称都是不同的，并且它们与最新日期相关。

All the distinct values are Dane, kim, Hong, Susan. I also want the rows with the latest dates associated with these distinct name. The list with entries I would like is the rows below. Notice Names are all distinct, and they are associated with the latest date.

 Name            email                 date
_________________________________________________

Dane            [e-mail]        2017-06-20
Kim             [e-mail]         2017-06-10
Hong            [e-mail]        2016-06-25
Susan           [e-mail]       2017-05-21

推荐答案

使用postgresql，您应该能够做到：

with postgresql you should able to do:

 EmailModel.objects.all().order_by('date').distinct('Name')

有关此类的更多方法/功能，您可以访问此处的文档

for more methods/functions like this, you can visit the docs here

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