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List:       postgresql-sql
Subject:    Re: [SQL] join returns too many results...
From:       Joshua Tolley <eggyknap () gmail ! com>
Date:       2010-10-04 13:24:39
Message-ID: 4ca9d59a.26798e0a.1059.25cf () mx ! google ! com
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On Sun, Oct 03, 2010 at 02:54:41PM -0400, Frank Bax wrote:
> Whatever clause I choose to add I *must* ensure that final result set  
> contains only one-to-one join between tables.  Either of these two  
> results is acceptable:
>
> For option 1; result C=All or C=Centre is acceptable.
> For option 2; result B=NE70 or B=NE75 or B=NE80 is acceptable.
>
> I am lost trying to construct SQL to accomplish this...

Try DISTINCT ON, after ensuring the results are ordered meaningfully.

http://www.postgresql.org/docs/current/interactive/sql-select.html#SQL-DISTINCT

--
Joshua Tolley / eggyknap
End Point Corporation
http://www.endpoint.com

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