Martijn van Oosterhout wrote:
On Tue, Sep 13, 2005 at 12:15:21PM -0700, Ben wrote:
Oracle has a very handy function called first_value, which can be used
to turn a set like this:
Look at DISTINCT ON ()
Does postgres have something equivalent, or, even better, is there a
reasonable way to express this in standard SQL?
In standard SQL, not really, which is why it's an extention...
No? It seems this is similar
SELECT a,b
FROM ( SELECT a,b,
RANK() OVER (
PARTITION BY a
ORDER BY b
) rank
FROM my_table )
WHERE rank = 1
ORDER BY a, rank DESC;
which I think is standard sql-99 with the sql-99 olap extention.
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