Re: pgsql aggregate: conditional max

Michael Fuhr wrote:

>SELECT DISTINCT ON (aid) aid, cat
>FROM tablename
>ORDER BY aid, weight DESC, cat;
>  
>
Good pointer. I think this will solve my problem. :)

>SELECT aid, cat
>FROM tablename AS t
>JOIN (SELECT aid, max(weight) AS weight
>      FROM tablename
>      GROUP BY aid) AS s USING (aid, weight);
>  
>
This query will return duplicates if there are multiple categories (for 
one aid) with the same max weight. Yet, I should be able to remove the 
duplicates somehow...:)

I really appreciate your help!

-- 
All best, 

Weimao

Weimao Ke
Indiana University Bloomington
School of Library and Information Science
http://ella.slis.indiana.edu/~wke