On Tue, May 06, 2008 at 01:22:30PM -0400, Kynn Jones wrote: > Suppose table X has two columns: class (TEXT) and size (INT). I want a > listing showing the (up to) 5 largest values of "size" for each value of > "class" (for some values of "class" the total number of available records > may be less than 5). > What would be the simplest way to achieve such a listing? It seems like > something one could do with GROUP BY, ORDER, and LIMIT, but I can't figure > out the right syntax for this query. get rownum(in_code TEXT) function from http://www.depesz.com/index.php/2007/08/17/rownum-anyone-cumulative-sum-in-one-query/ (it's important to use the version with in_code argument. then write: select * from (select class, size from X order by class asc size desc) q where rownum(class) <= 5; depesz -- quicksil1er: "postgres is excellent, but like any DB it requires a highly paid DBA. here's my CV!" :) http://www.depesz.com/ - blog dla ciebie (i moje CV)
