Sort data (order by) before group by in mysql

Question

I want to group below data from sub_prd_id. but before that i need order data from max created_at.

I wrote query as below.

Answer 1

What you're trying to accomplish is known as a groupwise maximum, which can't be achieved using ORDER BY. Instead, one must find the MAX() and then join the result back to the table:

SELECT prd_data.* FROM prd_data NATURAL JOIN (
  SELECT   sub_prd_id, MAX(created_at) created_at
  FROM     prd_data
  GROUP BY sub_prd_id
) t

See it on sqlfiddle.