On Mon, Aug 3, 2009 at 6:54 PM, Russell
Keith-Magee<[email protected]> wrote:
> To achieve this in SQL, you need to add an inner query for each
> summary column you want
this is what i'm doing:
q = Order.objects.all().extra ( select={
'num_items':'SELECT COUNT(*) FROM OT_item WHERE
order_id=OT_order.id',
'num_notyet' :'SELECT COUNT(*) FROM OT_item WHERE
order_id=OT_order.id AND status=1',
'num_proc' :'SELECT COUNT(*) FROM OT_item WHERE
order_id=OT_order.id
AND status=2',
'num_ready' :'SELECT COUNT(*) FROM OT_item WHERE
order_id=OT_order.id AND status_id=3',})
seems reasonably portable SQL (not that i plan to switch DBs), and
lines up nicely in the editor, so any typos are visible enough. It's
not my usual style on SQL; but it's the server's job to optimize it.
It looks like it's doing the exact same fetches as the equivalent
JOINs
tks a lot
--
Javier
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