On 09/09/2009, at 9:02 AM, David W Noon wrote:
On Tue, 8 Sep 2009 14:25:20 -0700, Scott Frankel wrote about [GENERAL]
where clauses and multiple tables:
Is it possible to join tables in the where clause of a statement?
[snip]
Given a statement as follows:
SELECT foo.foo_id, foo.name
FROM foo, bar
WHERE foo.bar_id = bar.bar_id
AND bar.name = 'martini';
Just use an IN predicate:
SELECT foo_id, name FROM foo
WHERE bar_id IN (SELECT bar_id FROM bar WHERE name = 'martini');
This is frequently called a semi-join.
By the way, folks, do you think there may be performance gain or loss
from rewriting this with an explicit JOIN? E.g.:
SELECT DISTINCT foo.foo_id, foo.name FROM foo JOIN bar ON foo.bar_id =
bar.bar_id WHERE bar.name='martini';
Thanks!
Yar
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