Django model inner join ORM issues

Question

suppose I have the following three models, see as follow: I wanna to construct a Django model query to archive the same effect as the following SQL statement.

SQL statement

select B.value, C.special
from B inner join C 
where B.version = C.version and B.order = C.order;

I got the following three models:

class Process(models.Model):
    name = models.CharField(max_length=30)
    description = models.CharField(max_length=150)

class ProcessStep(models.Model):
    process = models.ForeignKey(Process)
    name = models.CharField(max_length=30)
    ...
    order = models.SmallIntegerField(default=1)
    version = models.SmallIntegerField(null=True)

class Approve(models.Model):
    process = models.ForeignKey(Process)
    content = models.CharField(max_length=300)
    ...
    version = models.SmallIntegerField(null=True)
    order = models.SmallIntegerField(default=0)

I want to find all Approves that have the same (version, order) tuple matching against the ProcessStep model.

Answer 1

像这样吗

Approve.objects.filter(process__processstep_set__order=<value>)

Answer 2

Right now I can only come out with a solution by using raw SQL, see the following code.

from django.db import connection
cursor = connection.cursor()
cursor.execute("
SELECT A.id, B.id 
from approval_approve as A inner join approval_approvalstep as B
where A.process_id = B.process.id 
    and A.order = B.order 
    and A.version = B.version;")
# do something with the returned data

If you guys got any better solution, I would like to hear from you, thanks~