PostgreSQL DISTINCT and ORDER BY

[bubblenut]

I have a table which looks like this

blog.group_blog

blog integer primary key
groupid integer primary key
accepted integer
dateaccepted timestamp indexed

I want to get a list of groupids which have had blogs accepted on them most recently. So, I want a list of distinct groupids ordered by dateaccepted (descending). I've tried a number of queries all have which have failed (duh, that's why I'm posting here:p)
Here are some of them

SELECT groupid FROM blog.group_blog GROUP BY groupid ORDER BY dateaccepted DESC LIMIT 100;
SELECT DISTINCT groupid FROM blog.group_blog ORDER BY datecreated DESC LIMIT 100;
SELECT DISTINCT ON (groupid) groupid, dateaccepted FROM blog.group_blog ORDER BY datecreated DESC LIMIT 100;

Anyone got any other ideas for this problem?

Cheers
Rob

[Lars_Berg]

SELECT groupid , max(dateaccepted) as dc
FROM blog.group_blog 
GROUP BY groupid 
ORDER BY dc DESC 
LIMIT 100

[bubblenut]

Nah, Postgre doesn't like it if you'r order by isn't connected with the group by. I got around it with a sub-select in the end.
SELECT DISTONCT ON (groupid) groupid, dateaccepted FROM (SELECT groupid dateaccepted FROM blog.group_blog ORDER BY dateaccepted DESC) as foo LIMIT 100