Oracle查詢以找到最大關係

Question

我在Oracle

SELECT q2.Director_ID, q2.Actor_ID 
    FROM (SELECT MAX(n.Num_Joint_Movies) AS Max_Joint_Movies 
     FROM (SELECT d.Director_ID, A.Actor_ID, COUNT(*) AS Num_Joint_Movies 
       FROM Movies_Directors AS d 
       , Roles AS a 
       where d.Movie_ID = a.Movie_ID 
      GROUP BY d.Director_ID, A.Actor_ID 
      ) AS n 
    ) AS q3, 
(SELECT d.Director_ID, A.Actor_ID, COUNT(*) AS Num_Joint_Movies 
     FROM Movies_Directors AS d 
    , Roles AS a 
     where d.Movie_ID = a.Movie_ID 
    GROUP BY d.Director_ID, A.Actor_ID 
    ) AS q2 
where q3.Max_Joint_Movies = q2.Num_Joint_Movies 

有一個問題，但我得到的錯誤ORA-00907：缺少右括號

能否請你指導我什麼，我做錯了。

Answer 1

SELECT Director_ID, 
    Actor_ID FROM 
(SELECT 
    d.Director_ID, 
    a.Actor_ID, 
    COUNT(*) AS Num_Joint_Movies 
FROM 
    Movies_Directors AS d 
     JOIN Roles AS a 
     ON d.Movie_ID = a.Movie_ID 
    GROUP BY 
     d.Director_ID, 
     a.Actor_ID 
) WHERE ROWNUM = 1 ORDER BY Num_Joint_Movies ASC 
/

試試這個，它應該工作

Answer 2

您的SQL失敗，你已經使用了AS關鍵字的表連接。

即你應該有：

SELECT q2.Director_ID, q2.Actor_ID 
    FROM (SELECT MAX(n.Num_Joint_Movies) AS Max_Joint_Movies 
     FROM (SELECT d.Director_ID, A.Actor_ID, COUNT(*) AS Num_Joint_Movies 
       FROM Movies_Directors d 
       , Roles a 
       where d.Movie_ID = a.Movie_ID 
      GROUP BY d.Director_ID, A.Actor_ID 
      ) n 
    ) q3, 
(SELECT d.Director_ID, A.Actor_ID, COUNT(*) AS Num_Joint_Movies 
     FROM Movies_Directors d 
    , Roles a 
     where d.Movie_ID = a.Movie_ID 
    GROUP BY d.Director_ID, A.Actor_ID 
    ) q2 
where q3.Max_Joint_Movies = q2.Num_Joint_Movies; 

你的SQL可以簡化爲這樣的回答：如果我們增加一個等級

SQL> create table Movies_Directors(director_id, Movie_ID) 
    2 as 
    3 select 1, 1 from dual 
    4 union all 
    5 select 1, 2 from dual 
    6 union all 
    7 select 2, 3 from dual 
    8 union all 
    9 select 2, 4 from dual 
10 union all 
11 select 3, 1 from dual ; 

Table created. 

SQL> create table roles(movie_id, actor_Id) 
    2 as 
    3 select 1, 1 from dual union all 
    4 select 1, 2 from dual union all 
    5 select 1, 3 from dual union all 
    6 select 1, 4 from dual union all 
    7 select 2, 1 from dual union all 
    8 select 2, 3 from dual union all 
    9 select 3, 3 from dual union all 
10 select 3, 1 from dual; 

Table created. 

：

select Director_ID, Actor_ID, Num_Joint_Movies 
    from (select d.Director_ID, A.Actor_ID, COUNT(*) Num_Joint_Movies, 
       rank() over (order by count(*) desc) r 
        from Movies_Directors d 
         inner join Roles a 
           on d.Movie_ID = a.Movie_ID 
       group by d.Director_ID, A.Actor_ID) 
where r = 1; 

編輯一個小樣本分析： SQL> select d.Director_ID，A.Actor_ID，COUNT（*）Num_Joint_Movies， 2秩（）以上（以通過計數（*）降序）R 3從Movies_Directorsð 4內連接作用一個 5上d.Movie_ID = a.Movie_ID 6組由d.Director_ID，A.Actor_ID 7/

DIRECTOR_ID ACTOR_ID NUM_JOINT_MOVIES   R 
----------- ---------- ---------------- ---------- 
      1   1    2   1 
      1   3    2   1 
      2   3    1   3 
      1   2    1   3 
      3   2    1   3 
      3   3    1   3 
      3   4    1   3 
      2   1    1   3 
      1   4    1   3 
      3   1    1   3 

10 rows selected. 

現在剛過濾的秩1 ..

SQL> select Director_ID, Actor_ID, Num_Joint_Movies 
    2 from (select d.Director_ID, A.Actor_ID, COUNT(*) Num_Joint_Movies, 
    3     rank() over (order by count(*) desc) r 
    4        from Movies_Directors d 
    5         inner join Roles a 
    6           on d.Movie_ID = a.Movie_ID 
    7        group by d.Director_ID, A.Actor_ID) 
    8 where r = 1; 

DIRECTOR_ID ACTOR_ID NUM_JOINT_MOVIES 
----------- ---------- ---------------- 
      1   3    2 
      1   1    2 

VS原始（校正的）SQL： SQL> SELECT q2.Director_ID，q2.Actor_ID 2 FROM（SELECT MAX（N .Num_Joint _Movies）AS Max_Joint_Movies 3 FROM（SELECT d.Director_ID，A.Actor_ID，COUNT（*）AS Num_Joint_Movies 4 FROM Movies_Directorsð 5，角色一個 6，其中d.Movie_ID = a.Movie_ID 7 GROUP BY d.Director_ID ，A.Actor_ID 8）N 9）Q3， 10（SELECT d.Director_ID，A.Actor_ID，COUNT（*）AS Num_Joint_Movies 11 FROM Movies_Directorsð 12，角色一個 13其中d.Movie_ID =α。 Movie_ID 14 GROUP BY d.Director_ID，A.Actor_ID 15）Q2 16，在那裏q3.Max_Joint_Movies = q2.Num_Joint_Movies;

DIRECTOR_ID ACTOR_ID 
----------- ---------- 
      1   1 
      1   3 

SQL>