MySQL order by before group by

Question

There are plenty of similar questions to be found on here but I don\'t think that any answer the question adequately.

I\'ll continue from the current most popular qu

Answer 1

Just to recap, the standard solution uses an uncorrelated subquery and looks like this:

SELECT x.*
  FROM my_table x
  JOIN (SELECT grouping_criteria,MAX(ranking_criterion) max_n FROM my_table GROUP BY grouping_criteria) y
    ON y.grouping_criteria = x.grouping_criteria
   AND y.max_n = x.ranking_criterion;

If you're using an ancient version of MySQL, or a fairly small data set, then you can use the following method:

SELECT x.*
  FROM my_table x
  LEFT
  JOIN my_table y
    ON y.joining_criteria = x.joining_criteria
   AND y.ranking_criteria < x.ranking_criteria
 WHERE y.some_non_null_column IS NULL;