Re: Getting top 2 by Category

Perfect. Thank You. I knew there had to be something simple.

From: Peter Steinheuser [mailto:psteinheuser(at)myyearbook(dot)com]
Sent: Tuesday, January 11, 2011 11:52 AM
To: Ozer, Pam
Cc: pgsql-sql(at)postgresql(dot)org
Subject: Re: [SQL] Getting top 2 by Category

Well, if yoi have PG 8.4 and above -

select categoryid, magazineid from (
select row_number() over (partition by categoryid order by
categoryid,magazineid asc) as row_number,
categoryid, magazineid from magazinecategory) foo
where row_number < 3;
categoryid | magazineid
------------+------------
3 | 2
3 | 8
4 | 10
4 | 11
(4 rows)

On Tue, Jan 11, 2011 at 2:00 PM, Ozer, Pam <pozer(at)automotive(dot)com> wrote:

This is probably very simple but I am drawing a blank. Do I need to
create a cursor to iterate through a table to grab the top 2 magazines
per category? Here is my table and some data . The results I need are
at the bottom. Any help would be greatly appreciated:

CREATE TABLE magazinecategory

(

magazinecategoryid smallint NOT NULL ,

magazineid smallint,

categoryid smallint

);

INSERT INTO magazinecategory(

magazinecategoryid, magazineid, categoryid)

VALUES (1, 2, 3);

INSERT INTO magazinecategory(

magazinecategoryid, magazineid, categoryid)

VALUES (2, 8, 3);

INSERT INTO magazinecategory(

magazinecategoryid, magazineid, categoryid)

VALUES (3 9, 3);

INSERT INTO magazinecategory(

magazinecategoryid, magazineid, categoryid)

VALUES (4, 10, 4);

INSERT INTO magazinecategory(

magazinecategoryid, magazineid, categoryid)

VALUES (5, 11, 4);

INSERT INTO magazinecategory(

magazinecategoryid, magazineid, categoryid)

VALUES (6, 12,4);

The results I want are

CategoryID MagazineID

3 2

3 8

4 10

4 11

Pam Ozer

--
Peter Steinheuser
psteinheuser(at)myyearbook(dot)com