Every developer knows the horror of mysql sort/order by or select distinct using with group by. Mysql does group by before order by and you get mixed results not what you expected. This is a small solution with less performance problem:
SELECT * FROM
select * from `my_table` order by timestamp desc
) as my_table_tmp
group by catid
order by nid desc
In this example we get latest news in each category. We create a temp table by sorting by timestamp and group by after it. It worked for me.
useful stuff 🙂
What's wrong with
select * from my_table group by catid order by catid, timestamp desc, nid desc;
Nothing wrong except your code will group by catid just before sorting by timestamp desc, so you will not get the latest timestamps for your grouped records.