> Now, I want to find all objects that have at most properties 1,2,3, say
(so
> something with (1,2) is okay, as is (1,2,3)). I can't see a way to do
this
> -- can anyone help?
It sounds like you are trying to find all objects that do not have any
properties outside of a specific list. One way to get that list is:
That's exactly right.
SELECT a_id
FROM a
WHERE
NOT EXISTS
(SELECT 1
FROM b
WHERE
b.a_id = a.a_id
AND
b.property NOT IN (1, 2, 3)
)
;
Yupp, this appears to do it! The 'double negation' is very clever.
Thanks a lot,
DL
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