Raymond O'Donnell wrote:
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?
The physical order that they appear will take care of that.
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