带有limit的mysql order by

Question

我有一个查询，我想从一个表中获得20个最受欢迎的位置，然后按字母顺序排序。我想知道是否有更干净或更有效的方法来做这件事？

SELECT
  city
FROM (
  SELECT 
    city, 
    count(*) AS cnt
  FROM locations 
  GROUP BY city
  ORDER BY cnt DESC
  LIMIT 20
) s ORDER BY city;

Answer 1

稍微干净一点：

SELECT city FROM (
  SELECT city FROM locations 
  GROUP BY city
  ORDER BY count(*) DESC
  LIMIT 20
) s ORDER BY city

如果您不打算使用count(*)，则不需要检索它。