From: | Tarlika Elisabeth Schmitz <postgresql(at)numerixtechnology(dot)de> |
---|---|
To: | "A(dot) Kretschmer" <andreas(dot)kretschmer(at)schollglas(dot)com> |
Cc: | pgsql-sql(at)postgresql(dot)org |
Subject: | Re: 3 SELECTs rolled into 1 ? |
Date: | 2008-06-04 12:14:58 |
Message-ID: | 20080604131458.03c90540@dick.coachhouse |
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Lists: | pgsql-sql |
On Wed, 4 Jun 2008 09:55:46 +0200
"A. Kretschmer" <andreas(dot)kretschmer(at)schollglas(dot)com> wrote:
> am Wed, dem 04.06.2008, um 8:41:29 +0100 mailte Tarlika Elisabeth
> Schmitz folgendes:
> > I have 3 similar SELECTs. I am wondering whether they could be
> > rolled into one?
> >
> >
> > SELECT
> > item.id,
> > department.id || section.id || category.id as x
> > FROM item
> > LEFT JOIN product ON ...
> > LEFT JOIN department ON ...
> > LEFT JOIN section ON ...
> > LEFT JOIN category ON ...
> >
> > ...
> >
> > SELECT
> > item.id,
> > department.id as x
> > FROM item
> > LEFT JOIN product ON ...
> > LEFT JOIN department ON ...
>
>
> If i understand you correctly: use UNION, like
>
> select foo1 as foo, bar1 as bar from table1 UNION ALL select foo2,
> bar2 from table2;
>
> The result table contains 2 columns foo and bar and all rows from both
> selects.
Many thanks!
Yes, this produces the desired result.
It is more or less just a concatenation of virtually identical SELECTs
with the same long WHERE clause. I had hoped to be able to express it
with a single SELECT. ;-)
--
Best Regards,
Tarlika Elisabeth Schmitz
A: Because it breaks the logical sequence of discussion
Q: Why is top posting bad?
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