DISTINCT is a very simple solution! But I have one problem: In addition to the FIRST fields, I also do want some aggregate functions. More accurately, it would be: SELECT grouping_field, FIRST(field_a), FIRST(field_b), SUM(field_x), MAX(field_y) ... How should I do that? Should I do two queries with a join on the grouping field? Or is there a more direct way? On 12/31/12, Jack Christensen <jack@xxxxxxxxxxxxxxxxxxx> wrote: > 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/ > > > > -- > Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-general > -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
