I've got a table of "coupons" which have an expiration date. For each type of coupon, I'd like to get the primary key of the coupon which will expire first.
# create table coupon ( coupon_id serial primary key, type varchar(255), expires date ); insert into coupon values(DEFAULT,'free','2007-01-01'); insert into coupon values(DEFAULT,'free','2007-01-01'); insert into coupon values(DEFAULT,'free','2007-06-01'); insert into coupon values(DEFAULT,'free','2007-06-01'); insert into coupon values(DEFAULT,'50%','2008-06-01'); insert into coupon values(DEFAULT,'50%','2008-06-02'); insert into coupon values(DEFAULT,'50%','2008-06-03'); The desired query would look like: # select coupon_id,type,expires from coupon where type='free' order by expires limit 1; coupon_id | type | expires -----------+------+------------ 1 | free | 2007-01-01 But be grouped by type: # select type,min(expires),count(*) from coupon group by type; type | min | count ------+------------+------- free | 2007-01-01 | 4 ; pk=1 50% | 2008-06-01 | 3 ; pk=5 In the second example, is it possible to get the primary key of the row with the minimum expires time? -- ---- Visit http://www.obviously.com/ ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster