Question

我想选择电影参与度最高的演员

我知道

SELECT name,COUNT(name) AS counter
FROM actors a
INNER JOIN movies_actors ma ON a.a_id = ma.a_id
INNER JOIN movies m ON m.m_id = ma.m_id
GROUP BY name
ORDER BY counter DESC

它将显示参与电影的所有演员，并将计算他们的参与但是我怎样才能只展示参与度最高的演员* / actors *

我正在使用SQL Server 2012

Answer 1

你可以这样说（未经测试）;

with actors ( name , counter , rank )
as
( SELECT name    = a.name   ,
         counter = COUNT(*) ,
         rank    = rank() over ( order by count(*) desc )
  FROM actors        a
  JOIN movies_actors ma ON a.a_id = ma.a_id
  JOIN movies        m  ON m.m_id = ma.m_id
  GROUP BY name
)
select *
from actors
where rank = 1

或（稍微简单一些）

select *
from ( SELECT name    = a.name   ,
              counter = COUNT(*) ,
              rank    = rank() over ( order by count(*) desc )
       FROM actors        a
       JOIN movies_actors ma ON a.a_id = ma.a_id
       JOIN movies        m  ON m.m_id = ma.m_id
       GROUP BY name
     ) t
where t.rank = 1

或者您可以避免对结果集进行分区并使用以下内容对其进行排名：

select t.movies , a.*
from ( select actor_id = a_id ,
              movies   = count(*)
       from movies_actors 
       group by a_id
     ) t
join ( select max_movie = max( t.movie_count )
       from ( select actor_id    = a_id ,
                     movie_count = count(*)
              from movies_actors
              group by a_id
            ) t
      ) x on x.max_movies = t.movies
join actors a on a.id = t.a_id

Answer 2

大多数数据库都支持窗口/分析功能，包括SQL Server 2012.函数max()在这里非常有用：

SELECT name, counter
FROM (SELECT name, COUNT(*) AS counter, MAX(COUNT(*)) OVER () as maxcounter
      FROM actors a INNER JOIN
           movies_actors ma
           ON a.a_id = ma.a_id INNER JOIN
           movies m
           ON m.m_id = ma.m_id
      GROUP BY name
     ) n
WHERE counter = maxcounter;

在SQL中显示所有具有最大计数（*）的名称

2 个答案: