On Saturday 04 October 2003 10:56, Christopher Kings-Lynne wrote: > Hi guys, > > If I have a table that is just a single column full of numbers, how can > I select all the rows from the table with a second column that is the > running tally so far down the result set? > > eg: > > Num Tally so far > 0.3 0.3 > 1.2 1.5 > 2.0 3.5 > ... > > Does this require PL/PgSQL coding? If so, how do you actually construct > an arbitrary row for returning? The docs are somewhat unclear on this.
Did you post this days ago, or is your/my clock wrong - it reads 2003-10-04 in my mailer? Anyway, you could do it with a sub-query, but performance will be less than great with a large result-set. SELECT * FROM runtot ; idx | num -----+----- 1 | 10 2 | 20 3 | 30 CREATE FUNCTION runtot_sum(int4) RETURNS int4 AS 'SELECT sum(num)::int4 FROM runtot WHERE idx <= $1' LANGUAGE 'SQL'; SELECT idx, num, runtot_sum(idx) FROM runtot ORDER BY idx; idx | num | runtot_sum -----+-----+------------ 1 | 10 | 10 2 | 20 | 30 3 | 30 | 60 Procedural is the way to go if you have a large result set. Stephan Szabo has written some good notes on set-returning functions: http://techdocs.postgresql.org/guides/SetReturningFunctions Basically, define a type: CREATE TYPE run_tot_type AS ( a whatever, b whatever, run_tot whatever ); Then: CREATE FUNCTION my_run_tot() RETURNS SETOF run_tot_type AS... Accumulate your values in a record-type variable and use RETURN NEXT to issue each row. HTH -- Richard Huxton Archonet Ltd ---------------------------(end of broadcast)--------------------------- TIP 3: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly
