Thanks very much, Tom. While the DISTINCT ON suggestion answered the question I asked very neatly and I am glad to add that concept to my arsenal, your standard-compliant query was what I actually needed. The DISTINCT ON query only gave me one coil if there were two coils in a charge that had the same coldspot time. Your standard-compliant query included them. There is a fourth column of interest, named coil_trf. The purpose of this exercise is to map coil_trf values to coldspot times for the coils in each charge that have the largest coldspot time. If two coils have the same coldspot time and none of the others in the charge have one as long, then I want both coils. The key concept here that I didn't know about was the use of more than one field in a list used with IN. Using actual field names from the database (except for coil_trf, which I haven't added yet because it comes from another table), here's the query I ended up with: select coil_id, inventory.charge, heating_coldspot_time_reached from inventory inner join charge on charge.charge = inventory.charge where base_type = '3' and heating_coldspot_time_reached > 0 and inventory.status = 'Done' and inventory.charge >= 1000 and (inventory.charge, heating_coldspot_time_reached) in (select inventory.charge, max(heating_coldspot_time_reached) from inventory inner join charge on charge.charge = inventory.charge where base_type = '3' and heating_coldspot_time_reached > 0 and inventory.status = 'Done' and inventory.charge >= 1000 group by inventory.charge) order by inventory.charge RobR -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
