Re: [SQL] unmatched

prova=> select * from prova1;
a1
-----
delta
alpha
gamma
(3 rows)

prova=> select * from prova2;
a2
-----
delta
gamma
(2 rows)

prova=> select * from prova1 where a1 not in (select * from prova2);
a1
-----
alpha
(1 row)

"Brett W. McCoy" ha scritto:

> I seem to have a serious brain fart going here. I have two tables, and
> I want to find out which rows that are in the first do not have a match
> in the second. If I could create an explicit left join, I could do it by
> finding the rows in the second column that are NULL. Here's what I kinda
> have, but itjust sits there and never returns anything:
>
> select count(*) from apdf
> where apdf.doc_index != ondisk.doc_index;
>
> I tried the NOT IN operator (!!=), but it didn't like that at all. Is !=
> a valid operator?
>
> Brett W. McCoy
> http://www.lan2wan.com/~bmccoy
> -----------------------------------------------------------------------
> "Biology is the only science in which multiplication means the same
> thing as division."

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PostgreSQL 6.5.0 on i586-pc-linux-gnu, compiled by gcc 2.7.2.3
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Jose'