Question

我有两个表：“城市”和“提交”。

我想选择至少有n个提交内容的城市列表。最好的方法是什么？同样重要的是，大多数城市的提交数量将少于n个。

我已经尝试选择所有城市，然后通过对提交进行COUNT（*）查询来重新过滤列表，但这显然是一个非常低效的解决方案。任何帮助表示赞赏。

Answer 1

试试这个：

SELECT Cities.id
FROM Cities
JOIN Submissions ON Cities.id = Submissions.CityId
GROUP BY Cities.id
HAVING COUNT(*) >= n

Answer 2

   select cityname, count(submissionid) as submissioncount
   from cities inner join submissions
   on submissions.cityid = cities.cityid
   group by cityname
   having count(submissionid) >= {yourdesiredcount}

SQL：仅选择是否满足最小行数

2 个答案: