On 12/31/2012 8:33 AM, Robert James wrote:
I have a query
SELECT grouping_field, MIN(field_a), MIN(field_b)
FROM ...
GROUP BY grouping_field
But, instead of picking the MIN field_a and MIN field_b, I'd like to
pick field_a and field_b from the first record, according to an order
I'll specify. In pseudo-SQL, it would be something like this:
SELECT grouping_field, FIRST(field_a), FIRST(field_b)
FROM ...
ORDER BY field_c DESC, field_d ASC, myfunc(field_e) ASC
GROUP BY grouping_field
How can I do that with Postgres?
select distinct on (grouping_field), field_a, field_b
from ...
order by grouping_field, field_a asc, field_b asc
http://www.postgresql.org/docs/9.2/static/sql-select.html#SQL-DISTINCT
--
Jack Christensen
http://jackchristensen.com/
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