MySQL 3.23/4.0/4.1 and 5.1 states:
If you use
GROUP BY[ for
select], output rows are sorted according to the
GROUP BYcolumns as if you had an
ORDER BYfor the same columns. ➫➫➫
However, MySQL 5.5 states:
Relying on implicit
GROUP BYsorting in MySQL 5.5 is deprecated. To achieve a specific sort order of grouped results, it is preferable to use an explicit
ORDER BYclause. ➫➫➫
What exactly does "deprecated" mean in MySQL?
Is the behavior of implicit
group by still guaranteed to work on MySQL 5.5, 5.6, and 5.7 (the current latest version) just like in every single version before that?
ORDER BY NULL still required to stop MySQL from doing needless sorting?
Edit (by Rick James)
This covers database issues:
- The ordering of a
- The meaning and usefulness of
ORDER BY NULL
- The wisdom of using a 'deprecated' 'feature'
- The meaning of "deprecated" in the MySQL manual (not just for this case)