How to use "group by and select the max one" in django

Question

I have a table in MySQL, like:

id  dirId filename
 1   1      jone
 2   1      jack
 3   2      jack
 4   3      ella

I want to get the biggest dir_id(and filename) with the same filename. We can use group by in MySQL, what to use in django?

Probably duplicated of https://stackoverflow.com/questions/2884509/django-select-max-id — Henrique Andrade, Jul 23 '18 at 04:23

score 0 · Answer 1 · answered Aug 15 '18 at 08:09

0

I used those code to get it:
1.A1=ModelClass.objects.all() 2.A2=A1.values_list('filename',flat='True').distinct() 3.for itr in A2: A1.filter(filename=itr).order_by('dirId') don't know it's fast enough.

answered Aug 15 '18 at 08:09

Joe

1
1

score -1 · Answer 2 · answered Jul 23 '18 at 04:31

-1

you can use group by syntax in django like this.

ModelClass.objects.filter(...).values('filename').annotate(dir_id=models.Max('dirId'))

answered Jul 23 '18 at 04:31

vorujack

1,778
16
22

How to use "group by and select the max one" in django

2 Answers2