sql - 在 oracle 中使用 group by 不是用于 count(*) 而是用于 min() 函数

Question

如何对 3 列使用 group by 它显示它不是 group by 表达式的错误。这是查询。

select
   brewer.name as brewer,beer.name as beer,count(ratings.score) as LowestRating
from ratings,beer,brewer
where ratings.beer=beer.id and beer.brewer=brewer.id
group by brewer,beer; 

Answer 1

您应该GROUP BY按列，而不是整个表：

select
     brewer.name as brewer,
     beer.name as beer,
     count(ratings.score) as LowestRating
  from
    ratings,
    beer,
    brewer
where
  ratings.beer = beer.id
  and beer.brewer = brewer.id
group by brewer.name, beer.name;