MySQL : only_full_group_by multiple date isn't in group by

Question

How is the correct query when only_full_group_by activated?

SELECT
    MAX(DATE (`date`)) AS `date_full`,
    WEEKDAY(`date`) AS `date_week`,
    COUNT(`id`) AS `visits`
    FROM `xxx_visits_stats` 
    WHERE YEAR(`date`) = YEAR("2017-01-01") 
    GROUP BY `date_week`
    ORDER BY `date` DESC

Without(disabled) only_full_group_by it works!

Answer 1

I think your problem is due to the fact that you're ordering by a column that's not mentioned in the GROUP BY and also not an aggregate.

Try this:

  SELECT MAX(DATE(`date`)) AS `date_full`,
         WEEKDAY(`date`) AS `date_week`,
         COUNT(`id`) AS `visits`
    FROM `xxx_visits_stats` 
   WHERE YEAR(`date`) = YEAR("2017-01-01") 
   GROUP BY WEEKDAY(`date`)
   ORDER BY 1 DESC

That form of ORDER BY means use the first column in the SELECT clause for ordering.