Dual Metric Aggregation with UNION ALL in SQL

Question

Given `movies`, `users`, and `movie_rating`, write a query to find: 1) the user who has rated the greatest number of movies (tie-break by user name alphabetical); 2) the movie with the highest average rating in February 2026 (tie-break by title).

Accepted Answer

Optimal Solution:
(
  SELECT u.name AS results
  FROM movie_rating mr
  JOIN users u ON mr.user_id = u.user_id
  GROUP BY u.user_id, u.name
  ORDER BY COUNT(mr.movie_id) DESC, u.name ASC
  LIMIT 1
)
UNION ALL
(
  SELECT m.title AS results
  FROM movie_rating mr
  JOIN movies m ON mr.movie_id = m.movie_id
  WHERE mr.created_at >= '2026-02-01' 
    AND mr.created_at < '2026-03-01'
  GROUP BY m.movie_id, m.title
  ORDER BY AVG(mr.rating) DESC, m.title ASC
  LIMIT 1
);

Technical Explanation:
Wrap two distinct top-1 queries in parentheses and concatenate them with `UNION ALL`.

movie_id	user_id	rating	created_at
1	1	3	2026-02-12
2	1	4	2026-02-15
1	2	5	2026-02-14

results
User One
Movie One