如何在django中查询为GROUP BY？ [英] How to query as GROUP BY in django?

问题描述

我查询一个模型，

Members.objects.all()

，并返回说

Eric, Salesman, X-Shop
Freddie, Manager, X2-Shop
Teddy, Salesman, X2-Shop
Sean, Manager, X2-Shop

我想要的是，知道最好的Django方式，将
a group_by查询发送到我的数据库，如同

What i want is, to know the best Django way to fire a group_by query to my db, as like,

Members.objects.all().group_by('designation')

当然不行。
我知道我们可以在django / db / models / query.py，
上做一些技巧，但我只是好奇地知道如何在没有修补的情况下执行。

Which doesn't work of course. I know we can do some tricks on "django/db/models/query.py", but i am just curious to know how to do it without patching.

推荐答案

如果你想做聚合，你可以使用 ORM的聚合功能：

If you mean to do aggregation you can use the aggregation features of the ORM:

from django.db.models import Count
Members.objects.values('designation').annotate(dcount=Count('designation'))

这将产生一个类似于

SELECT designation, COUNT(designation) AS dcount
FROM members GROUP BY designation

，输出的形式为

and the output would be of the form

[{'designation': 'Salesman', 'dcount': 2}, 
 {'designation': 'Manager', 'dcount': 2}]

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