Re: How to force select to return exactly one row

My understanding of UNION ALL is that it won't sort the rows...?

-----Original Message-----
From: pgsql-general-owner@postgresql.org [mailto:pgsql-general-owner@postgresql.org] On Behalf Of Tim Landscheidt
Sent: Tuesday, 22 June 2010 9:41 AM
To: pgsql-general@postgresql.org
Subject: Re: [GENERAL] How to force select to return exactly one row

Brett Mc Bride <brett.mcbride@deakin.edu.au> wrote:

> How about:
> SELECT * from (
> SELECT somecolumns
>  FROM ko
> LEFT JOIN t1 ON t1.primarykey= ko.t1foreignkwey
> ...
> LEFT JOIN tn ON tn.primarykey= ko.tnforeignkwey
> WHERE ko.primarykey='someprimarykeyvalue'
> UNION ALL
> SELECT default_value
> )
> LIMIT 1;
> [...]

... with a proper "ORDER BY" clause.

Tim


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