Question

我试图基本上将一个计数除以SQL中另一个表的数字查询

MOVIECOUNT AS (
  SELECT COUNT(MS.MOVID) AS MOVCOUNT, MG.GENRE AS GENREPERCOUNT
  FROM MOVIESUCCESS MS
  INNER JOIN MOVIES_GENRES MG ON MG.MOVIE_ID = MS.movid 
  group by MG.GENRE
)

SELECT (MC.MOVCOUNT / COUNT(DG.MOVIE_ID))
FROM MOVIECOUNT MC, DIRECTORS_GENRES DG
WHERE MC.GENREPERCOUNT = DG.GENRE
GROUP BY DG.GENRE

我无法让后一部分进行编译（MOVIECOUNT可以正常工作 - 仅供参考）。架构的其余部分并不重要，我让其余的代码工作。我基本上只是试图获得我在moviecount中找到的计数（按类型完成）并将其除以相同类型的所有电影的计数。想法？ Oracle SQL

Answer 1

您可能需要在加入之前单独计算每个聚合：

with mgc as (
  select
    mg.genre,
    count(*) as moviecount
  from
    moviesuccess ms
      inner join
    movies_genres mg
      on mg.movie_id = ms.movid
  group by
    mg.genre
), dgc as (
  select
    dg.genre,
    count(*) as directorcount
  from
    directors_genres dg
  group by
    dg.genre
) select
  mgc.genre,
  mgc.moviecount / dgc.directorcount
from
  mgc
    inner join
  dgc
    on mgc.genre = dgc.genre;

Answer 2

您可以使用您正在采用的方法执行此操作，您只需要更加小心聚合：

WITH MOVIECOUNT AS (
      SELECT COUNT(MS.MOVID) AS MOVCOUNT, MG.GENRE AS GENREPERCOUNT
      FROM MOVIESUCCESS MS INNER JOIN
           MOVIES_GENRES MG
           ON MG.MOVIE_ID = MS.movid 
      group by MG.GENRE
    )
SELECT (MC.MOVCOUNT / COUNT(DG.MOVIE_ID))
FROM MOVIECOUNT MC JOIN
     DIRECTORS_GENRES DG
     ON MC.GENREPERCOUNT = DG.GENRE
GROUP BY MC.GENRE, MC.MOVCOUNT;

将计数除以SQL中的计数查询

2 个答案: