James, I know Postgresql doesn't have 2 arg aggregate functions. what you could do is the following (untested)
select distict product_id, sum(case when purchased then 1 else 0 end) as purchased, sum(case when was_selected then 1 else 0 end) as was_selected from some_table group by product_id; Jim ---------- Original Message ----------- From: "James Moliere" <[EMAIL PROTECTED]> To: <pgsql-sql@postgresql.org> Sent: Fri, 7 Jul 2006 06:53:45 -0700 Subject: [SQL] create aggregate function 'count_bool( column_name, boolean )' > Hello, > I'd like to create a function called count_bool( column_name, boolean ) in > PostgreSQL. > > this function is similar to the count( column_name ) function but will only > count the trues or falses based on the other input parameter boolean. e.g. > if you pass in a 'true', all the trues will be counted but not the falses -- > it's the same but opposite if the 'false' was passed in. > > I'd like this aggregate function to be developed with the SQL language > instead of 'C' (for maintenance reasons). From the surface, it appears to > be an incredibly simple job only to find that it's difficult. > > In some respects, I can't believe this function doesn't exist in SQL > > so now I can create the statement > select distict product_id, count_bool(purchased, true), > count_bool(was_selected, true) from some_table group by product_id; > > instead of breaking the query into 3 seperate queries > > select distict product_id from some_table; > select count(purchased) from product_id where purchased = true; > select count(was_selected) from some_table where was_selected = true; > > Am I missing a detail with SQL based aggregate function development? > > Any help would be appreciated. > > Thanks! ------- End of Original Message ------- ---------------------------(end of broadcast)--------------------------- TIP 2: Don't 'kill -9' the postmaster
