On Nov 19, 2005, at 7:49 , Jeremy Palmer wrote:
SELECT DISTINCT ON (vector_id, obs_type)
id
FROM observation
ORDER BY vector_id,
obs_type,
date DESC;
However the documentation also states that "DISTINCT ON" is not
part of the
SQL standard and should be avoided when possible, stating that
aggregations
and sub-queries should be used instead...
How would this be done in this scenario?
Something like:
select max(date), id
from observation
group by vector_id, obs_type;
Do test to see which is better in your situation.
Michael Glaesemann
grzm myrealbox com
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