Question

查询连接最多的顶点/元组是什么样的 - 谁是电影最多的演员？

例如，再次电影和演员样本表：

Movies (moviesID, title)
Actors (actorsID, name)
Relations (moviesID, actorsID)

可能使用内连接？一个例子很棒 - 谢谢

Answer 1

如果您只想要actorsId，则无需加入：

select top 1 actorsId, count(*) as nummovies
from relations r
group by actorsId
order by nummovies desc;

因为可能存在重复项，您可能需要top 1 with ties：

select top 1 with ties actorsId, count(*) as nummovies
from relations r
group by actorsId
order by nummovies desc;

此外，由于演员可以在同一部电影中拥有多个角色，如果数据库中有不同的角色，请选择count(distinct)：

select top 1 with ties actorsId, count(distinct moviesId) as nummovies
from relations r
group by actorsId
order by nummovies desc;

Answer 2

SELECT TOP 1
            A.actorsID, A.name, COUNT(R.moviesID) AS MovieCount
FROM        Actions     A
INNER JOIN  Relations   R       ON A.actorsID = R.actorsID
GRROUP BY   A.actorsID, A.name
ORDER BY    MovieCount DESC

大多数连接的“顶点”的SQL查询

2 个答案: