Yes, you can - but not in models.py! I have created a query.py and defined all models for raw queries in that file. Then I do raw SQL as defined here: https://docs.djangoproject.com/en/dev/topics/db/sql/
But you won't be able to update/insert data using this models. regards H. >reply to message: >date: 30.08.2011 02:02:13 >from: "graeme" <graeme.piete...@gmail.com> >to: "Django users" <django-users@googlegroups.com> >subject: [<django-users.googlegroups.com>] Re: Combining queries? A "join" in >Python? > > > >On Aug 30, 6:25 am, Tim <timothyp...@gmail.com> wrote: >> worst case you could always just write the sql query? >> >> https://docs.djangoproject.com/en/dev/topics/db/sql/ >> > >I have been looking at that already, what I have not yet figured out >is how the results map to models if I do a join in the SQL query. Can >it create the models for the joined tables as well? > >> On Aug 29, 8:15 am, graeme <graeme.piete...@gmail.com> wrote: >> >> >> >> >> >> >> >> > I looks like my attempt to simplify and abstract the problem just made >> > it harder to help me: my apologies for that. I was trying to combined >> > two different problems rather than ask two questions. Thanks for >> > helping despite that. >> >> > I think I have a solution for most of my problems, as far as getting >> > the queries working. I might be back with questions about >> > optimisation, but I can live with a little inefficiency in the query I >> > need to get working first. >> >> > On Aug 28, 4:33 am, Matteius <matte...@gmail.com> wrote: >> >> > > Since you are combining two sets of different objects you'll want >> > > Gelonida's response. Additionally, Use Q to create more logically >> > > advanced queries. I find your language difficult to gather what query >> > > you are looking for exactly, but here is an example of what I think >> > > you might mean: >> >> > > from django.db.models import Q >> >> > > the_Ds = D.objects.all().filter(b=B) >> > > the_Es = E.objects.all().filter(c=C) >> >> > > combined = the_Ds | the_Es >> >> > > # Other Example (an & requires both constraints to be met, and an Or >> > > will include the set of all matches. >> > > the_As = A.objects.all().filter(Q(constraint1) & Q(constraint2)) >> > > the_Bs = B.objects.all().filter(Q(constraint1) | Q(constraint2)) >> >> > > -Matteius >> >> > > Don't overlook how powerful this is because Django has Manager classes >> > > so you can make your constraints refer to both local properties and >> > > foreign key constraints as well as properties within the foreign key >> > > lookups. You may find that you wish to edit your schema relationship, >> > > perhaps by pointing backwards or reversing the relationship. It is >> > > hard to say with the categorical A, B, C, D example, but hope this >> > > helps and Good Luck! >> >> > > On Aug 27, 3:47 pm, Gelonida N <gelon...@gmail.com> wrote: >> >> > > > On 08/27/2011 11:39 AM, graeme wrote: >> >> > > > > I have a some models related link this: >> >> > > > > A has a foreign key on B which has a foreign key on C >> >> > > > > I also have D with a foreign key on B, and E with a foreign key of C >> >> > > > > If I do A.filter(**args).select_related() I will get all the As, Bs, >> > > > > and Cs I want. >> >> > > > > How do I get the Ds with a foreign key on a B in my queryset >> > > > > (preferably filtered) and all Es with a foreign key on C (also >> > > > > preferably filtered) >> >> > > > > The best I have been able to come up with is to query for all the >> > > > > the >> > > > > Ds and Es I want, and combine them with the Bs and Cs in the view >> >> > > > > I have a similar problem with another site, except that there not >> > > > > every B I want has an A with a foreignkey pointing to it, so I cannot >> > > > > just do select_related on A. >> >> > > > > I am not worried about doing an extra query or two per page. What I >> > > > > want to avoid is doing an extra query for each object in a lengthy >> > > > > list. >> >> > > > You can 'or' two query sets with the '|' operator >> >> > > > so do >> > > > queryset1 = Mymodel.objects.all().filter(...) >> > > > qyeryset2 = Mymodel.objects.all().filter(...) >> >> > > > combined = queryset1 | queryset2 > >-- >You received this message because you are subscribed to the Google Groups >"Django users" group. >To post to this group, send email to django-users@googlegroups.com. >To unsubscribe from this group, send email to >django-users+unsubscr...@googlegroups.com. >For more options, visit this group at >http://groups.google.com/group/django-users?hl=en. > -- You received this message because you are subscribed to the Google Groups "Django users" group. To post to this group, send email to django-users@googlegroups.com. To unsubscribe from this group, send email to django-users+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/django-users?hl=en.
