[thelist] [sql] location of conditional
Paul Cowan
evolt at funkwit.com
Mon Aug 4 22:01:56 CDT 2003
joshua wrote:
> It seems, though, that in an OUTER join the location of the conditional
> could make a big difference? Wrong? Right?
oh my yes.
SELECT
*
FROM
A
LEFT JOIN B ON
(A.Foo = B.Foo)
AND (B.Shoesize = 9)
and
{ ... }
LEFT JOIN B ON
(A.Foo = B.Foo)
WHERE
(B.Shoesize = 9)
will give you totally different results. Given the following data:
Table A Table B
Foo Foo Shoesize
1 1 9
2 2 10
3
The first query will return
1 1 9
2 null null
but the second will only return
1 1 9
Paul
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