Re: Question About UNION

On 09/10/2008 17:36, Bill Thoen wrote:
> I'm trying to combine two tables, but I only want unique records based
> on the first two columns. Can UNION be used to join three-column tables
> but only include records based on the uniqueness of the first two
> columns? If not, how would I do this with PostgreSQL 8.1?

How do you decide which records you want? - e.g. given the following rows...

  (a, b, c)
  (a, b, d)

...how do you decide whether you the one with c or the one with d?

Ray.

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Raymond O'Donnell, Director of Music, Galway Cathedral, Ireland
rod@iol.ie
Galway Cathedral Recitals: http://www.galwaycathedral.org/recitals
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