您可以将派生表（subselect）用于组，例如：

select  t.weight_group, count(*) from (
    SELECT player_name,
           weight,
           CASE WHEN weight > 250 THEN 'over 250'
                WHEN weight > 200 AND weight <= 250 THEN '201-250'
                WHEN weight > 175 AND weight <= 200 THEN '176-200'
                ELSE '175 or under' END AS weight_group
      FROM benn.college_football_players

  ) t 
  group by weight_group

你可以简单地使用相同的 case 中的表达式 group by 条款：

SELECT CASE WHEN weight > 250 THEN 'over 250'
            WHEN weight > 200 AND weight <= 250 THEN '201-250'
            WHEN weight > 175 AND weight <= 200 THEN '176-200'
            ELSE '175 or under' END AS weight_group,
       COUNT(*)
FROM benn.college_football_players
GROUP BY CASE WHEN weight > 250 THEN 'over 250'
            WHEN weight > 200 AND weight <= 250 THEN '201-250'
            WHEN weight > 175 AND weight <= 200 THEN '176-200'
            ELSE '175 or under' END