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我想知道我如何能够提取有多少导演，导演了一部电影或导演导演了多少部电影。例如，我让李安导演了两部电影。我想知道如何提取这些信息。我想知道如何查询他总共导演了两部电影。我感兴趣的另一类信息是《黑客帝国》有两位导演。我将如何询问矩阵有两个导演。这是我的代码：

CREATE TABLE MOVIE(
    MId INTEGER,
    Title VARCHAR(50),
    ReleaseDate DATE,
    Budget DOUBLE,
    PRIMARY KEY (MId)
);


CREATE TABLE DIRECTOR(
    DId INTEGER,
    Name VARCHAR(30),
    DateOfBirth DATE,
    PRIMARY KEY (DId)
);

CREATE TABLE DIRECTED(
    DirectorId INTEGER,
    MovieId INTEGER,
    PRIMARY KEY(DirectorId, MovieId),
    FOREIGN KEY(DirectorId) REFERENCES DIRECTOR(DId),
    FOREIGN KEY(MovieId) REFERENCES MOVIE(MId)
);

INSERT INTO MOVIE VALUES(1, 'Life of Pi', '2012-11-21', 120000000);
INSERT INTO MOVIE VALUES(3, 'Argo', '2012-10-12', 44500000);
INSERT INTO MOVIE VALUES(7, 'The Dark Knight Rises', '2012-07-20', 250000000);
INSERT INTO MOVIE VALUES(15, 'Thor', '2011-12-10', 150000000);
INSERT INTO MOVIE VALUES(45, 'The Sessions', '2012-01-23', 1000000);
INSERT INTO MOVIE VALUES(65, 'Batman Begins', '2005-06-15', 150000000);
INSERT INTO MOVIE VALUES(86, 'Goodfellas', '1990-09-19', 25000000);
INSERT INTO MOVIE VALUES(95, 'The Departed', '2006-10-06', 90000000);
INSERT INTO MOVIE VALUES(103, 'There's Something about Mary', '1998-07-15', 23000000);
INSERT INTO MOVIE VALUES(123, 'The Matrix', '1999-05-31', 63000000);
INSERT INTO MOVIE VALUES(144, 'Lust, Caution', '2007-09-28', 15000000);

INSERT INTO DIRECTOR VALUES(4, 'Ang Lee', '1954-10-23');
INSERT INTO DIRECTOR VALUES(5, 'Ben Affleck', '1972-08-15');
INSERT INTO DIRECTOR VALUES(8, 'Christopher Nolan', '1970-07-30');
INSERT INTO DIRECTOR VALUES(9, 'Kenneth Branagh', '1960-12-10');
INSERT INTO DIRECTOR VALUES(13, 'Ben Lewin', '1946-01-23');
INSERT INTO DIRECTOR VALUES(23, 'Martin Scorsese', '1942-11-17');
INSERT INTO DIRECTOR VALUES(25, 'Christopher Nolan', '1970-07-30');
INSERT INTO DIRECTOR VALUES(33, 'Peter Farrelly', '1956-12-17');
INSERT INTO DIRECTOR VALUES(34, 'Robert Farrelly', '1958-06-17');
INSERT INTO DIRECTOR VALUES(45, 'Lana Wachowski', '1965,06-21');
INSERT INTO DIRECTOR VALUES(46, 'Andrew Wachowski', '1967-12-29');

INSERT INTO DIRECTED VALUES(4, 1);
INSERT INTO DIRECTED VALUES(5, 3);
INSERT INTO DIRECTED VALUES(8, 7);
INSERT INTO DIRECTED VALUES(9, 15);
INSERT INTO DIRECTED VALUES(13, 45);
INSERT INTO DIRECTED VALUES(25, 65);
INSERT INTO DIRECTED VALUES(23, 86);
INSERT INTO DIRECTED VALUES(23, 95);
INSERT INTO DIRECTED VALUES(33, 103);
INSERT INTO DIRECTED VALUES(34, 103);
INSERT INTO DIRECTED VALUES(45, 123);
INSERT INTO DIRECTED VALUES(46, 123);
INSERT INTO DIRECTED VALUES(4, 144);
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2 回答 2

2

你需要JOIN，GROUP BY并COUNT()为此聚合

SELECT d.did, d.name director_name, COUNT(*) number_of_films
  FROM director d LEFT JOIN directed r
    ON d.did = r.directorid
 GROUP BY d.did, d.name

输出：

| DId | 导演姓名 | number_of_films |
|-----|--------------------|-----------------|
| 4 | 李安 | 2 |
| 5 | 本阿弗莱克 | 1 |
| 8 | 克里斯托弗·诺兰 | 1 |
| 9 | 肯尼斯·布拉纳 | 1 |
| 13 | 本·勒温 | 1 |
| 23 | 马丁斯科塞斯 | 2 |
| 25 | 克里斯托弗·诺兰 | 1 |
| 33 | 彼得·法雷利 | 1 |
| 34 | 罗伯特·法雷利 | 1 |
| 45 | 拉娜·沃卓斯基 | 1 |
| 46 | 安德鲁·沃卓斯基 | 1 |

与不止一位导演合作的电影

SELECT m.*, number_of_directors
  FROM 
(
  SELECT movieid, COUNT(*) number_of_directors
    FROM directed r
   GROUP BY movieid
  HAVING number_of_directors > 1
) q JOIN movie m
    ON q.movieid = m.mid

输出：

| 中间值 | 标题 | 发布日期 | 预算 | number_of_directors |
|-----|--------------|------------ -|----------|----------|
| 103 | 关于玛丽的事 | 1998-07-15 | 23000000 | 2 |
| 123 | 矩阵 | 1999-05-31 | 63000000 | 2 |

这是SQLFiddle演示

于 2013-09-20T23:25:36.580 回答
1 
select Name, count(DId)
from DIRECTED d inner join DIRECTOR m on d.DirectorId = m.DId
inner join MOVIE m on d.MovieId = m.mId
group by m.Title

http://sqlfiddle.com/#!5/28347/4/0

select m.Title, count(DId)
from DIRECTED d inner join DIRECTOR m on d.DirectorId = m.DId
inner join MOVIE m on d.MovieId = m.mId
group by Name

http://sqlfiddle.com/#!5/28347/6/0

于 2013-09-20T23:38:47.923 回答