O.k. So this is a very cut down example but it illustrates the question:
sqlite> create table a (a_id int primary key);
sqlite> create table b (b_id int primary key);
sqlite> create table ab (a_id int, b_id int, primary key(a_id, b_id));
sqlite> create table a_relation (a_id1 int, a_id2, primary key(a_id1,
a_id2));
sqlite> select * from a_relation where
...> a_id1 in (select a_id from ab where b_id = 1) and
...> a_id2 in (select a_id from ab where b_id = 1);
Is the select I'm doing where both a_id1 & 2 are "in" the exact same
select the most efficient way to do this? That is, is leaving it to the
query optimiser to figure out that I only need the sub select once the
best thing to do?
(The actual tables in question are a little more complicated and I have
versions to cope with but this effectively what I'm doing in C++ [so I'm
preparing and binding etc.]. The actual sub select have a group by a_id
to cope with multiple entries with different versions.)
Thanks
--
Matthew Jones
Hewlett-Packard Ltd
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