Just started in the last few days with django and am having a little
trouble with the orm. Is it possible to do a self join with an
aggregate? My query looks like the following (apologies for the
generic names):
SELECT t.field1, c.field2, c.field3, t.field4, t.field5, (t.field4/
t.field5) as "field6", t.field7
FROM ( SELECT field1, max(field7) as field7 FROM table1 GROUP BY
field1) x
JOIN table1 t
ON x.field1 = t.field1 AND x.field7 = t.field7
JOIN table2 c ON t.field1 = c.field8
For the moment I'm just using a custom manager, but I wasn't sure if
this was the best way to go. My code looks like the following:
class CustomManager(modelsManager):
def curr_quad(self):
cursor = connection.cursor()
cursor.execute("""
SELECT t.field1, c.field2, c.field3, t.field4, t.field5,
(t.field4/t.field5) as "field6", t.field7
FROM ( SELECT field1, max(field7) as field7 FROM table1 GROUP
BY field1) x
JOIN table1 t
ON x.field1 = t.field1 AND x.field7 = t.field7
JOIN table2 c ON t.field1 = c.field8 """)
return [row for row in cursor.fetchall()]
class Rdf_Qt(models.Model):
.
.
.
objects = CustomManager()
Thanks!
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