From: | Gavin 'Beau' Baumanis <gavinb(at)eclinic(dot)com(dot)au> |
---|---|
To: | pgsql-sql(at)postgresql(dot)org |
Subject: | distinct / group by assistance. |
Date: | 2008-06-28 14:32:40 |
Message-ID: | 6A8C2C63-A7E5-410B-B306-28F33D5C1D53@eclinic.com.au |
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Lists: | pgsql-sql |
Hi Everyone,
I am having some issues trying to create the required SQL that will
allow me to return the results I am after.
I have been trying various incarnations, using group by, sub-queries -
albeit to no avail - for the past three hours.
Consider the following simple SQL;
select
a.foo,
b.bar,
c.something
from
table1 a,
inner join
table2 b on b.id =a.id
left outer join
table3 on c.id = a.id
If there a multiple rows of the same id in table1, I get all
(multiple) rows - as you would expect - of course.
What I need however, is only one row returned per instance a.id that
is returned by the above query.
I thought of using group by - but there are no calculated fields...
and the real query contains 32 fields, which according to the errors I
ran into while trying to get this working, would all need to be
included in the group by clause.
So my understanding of group by is obviously a little dodgy - and
obviously not quite what I was expecting.
I tried using a sub query and select distinct a.id..... but that
didn't exactly help either.
I have deliberately included in my example the fact there is an outer
join too - I am not sue if that matters or not... but just in case
thought it prudent to include it here.
Thanks in advance for any help you might have.
Beau.
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