[development] SQL question.
Gordon Heydon
gordon at heydon.com.au
Fri Feb 3 04:17:39 UTC 2006
Hi,
I have been trying to work out a small sql issue, and I was wondering if
someone might be able to help me.
Basically I have 2 tables and I was to do a left join and pull out all
rows which has a value in the right hand table or doesn't exist.
eg.
SELECT a.a, a.b, b.a, b.c FROM a LEFT JOIN b ON a.a = b.a WHERE b.c =
'A';
So basically I want it to return.
a b a c
1 1 null null
2 2 2 A
etc.
Or do I need to 2 selects and merge them. When I do this now I get more
of an inner join instead of a left join. I am not sure how I say "or
doesn't exist".
Thanks in advance.
Gordon.
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