On Mon, Apr 23, 2018 at 12:47 PM, Alexander Farber < alexander.far...@gmail.com> wrote:
> SELECT > u.elo, > AVG(c.played - c.prev_played) AS avg_time_per_move, > (SELECT ROUND(AVG(score), 1) FROM words_moves > WHERE uid = u.uid) AS score, > > And I don't understand why adding a CTE has caused it, because without the > CTE the GROUP BY u.elo was not required... > > ​Adding "AVG(c.played - c.prev_played)" directly to the top-level select statement​ column list is what turned it into a "GROUP BY" query. When you embedded the "AVG(score)" in a subquery the GROUP BY was limited to just that subquery, and it had no other columns besides the aggregate and so didn't require a GROUP BY clause. David J.
