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Message Posted: Fri, 20 Feb 2004 @ 09:51:16 GMT
Subj: | | Re: Simple question about a left outer join... |
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From: | | Henry Runn |
Hi,
Those SQL's give different results
sel a.c1,a.c2,a.c3
from tbl1 a left outer join tbl2 b
on a.col1 = b.col1 and b.col1 is null;
=> will give all the rows from table a, because you have only join expression which tells how the join is going to be done and no
where clause to filter the rows
sel a.c1,a.c2,a.c3
from tbl1 a left outer join tbl2 b
on a.col1 = b.col1
where b.col1 is null;
=> will give the rows from table a which don't have value in table b because where clause is filtering rows
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