从 tbl1.x = tbl2.x = tbl3.x 的多个表中选择/加入

Question

我有一个电影数据库，需要执行一个查询，返回由同一个人编写、导演和制作的所有电影。

我在电影->制片人、电影->导演和电影->作家之间有多对多的关系，称为movie_director、movie_producer和movie_writer。这些表有一个外键指向名为 people 的表和一个指向 movies 表的外键。

如何选择一个且制片人、导演和编剧相同的电影？我已经尝试过这个 select 语句，但它返回了很多重复项：

SELECT movie_director.name
from movie_director, 
     movie_producer, 
     movie_writer
where movie_producer.name = movie_director.name = movie_writer.name;

创建movie_director：

CREATE TABLE `movie_director` (
  `title` VARCHAR(100) NOT NULL,
  `year` int NOT NULL,
  `name` VARCHAR(100) NOT NULL,
  PRIMARY KEY (`title`, `year`, `name`),
  INDEX `fk_movies_has_directors_name_idx` (`name` ASC),
  INDEX `fk_movies_has_directors_titleyear_idx` (`title` ASC, `year` ASC),
  CONSTRAINT `fk_movies_has_directors_titleyear`
    FOREIGN KEY (`title` , `year`)
    REFERENCES `mdb`.`movies` (`title` , `year`)
    ON DELETE cascade
    ON UPDATE cascade,
  CONSTRAINT `fk_movies_has_directors_name`
    FOREIGN KEY (`name`)
    REFERENCES `mdb`.`directors` (`name`)
    ON DELETE cascade
    ON UPDATE cascade)
    ENGINE INNODB;

创建movie_director：

CREATE TABLE `movie_producer` (
 `title` VARCHAR(100) NOT NULL,
  `year` int NOT NULL,
  `name` VARCHAR(100) NOT NULL,
  PRIMARY KEY (`title`, `year`, `name`),
  INDEX `fk_movies_has_producers_name_idx` (`name` ASC),
  INDEX `fk_movies_has_producers_titleyear_idx` (`title` ASC, `year` ASC),
  CONSTRAINT `fk_movies_has_producers_titleyear`
    FOREIGN KEY (`title` , `year`)
    REFERENCES `mdb`.`movies` (`title` , `year`)
    ON DELETE cascade
    ON UPDATE cascade,
  CONSTRAINT `fk_movies_has_producers_name`
    FOREIGN KEY (`name`)
    REFERENCES `mdb`.`producers` (`name`)
    ON DELETE cascade
    ON UPDATE cascade)
    ENGINE INNODB;

创建movie_writer：

CREATE TABLE `movie_writer` (
 `title` VARCHAR(100) NOT NULL,
  `year` int NOT NULL,
  `name` VARCHAR(100) NOT NULL,
  PRIMARY KEY (`title`, `year`, `name`),
  INDEX `fk_movies_has_writers_name_idx` (`name` ASC),
  INDEX `fk_movies_has_writers_titleyear_idx` (`title` ASC, `year` ASC),
  CONSTRAINT `fk_movies_has_writers_titleyear`
    FOREIGN KEY (`title` , `year`)
    REFERENCES `mdb`.`movies` (`title` , `year`)
    ON DELETE cascade
    ON UPDATE cascade,
  CONSTRAINT `fk_movies_has_writers_name`
    FOREIGN KEY (`name`)
    REFERENCES `mdb`.`writers` (`name`)
    ON DELETE cascade
    ON UPDATE cascade)
    ENGINE INNODB;

感谢所有帮助或指向有用信息的链接！

Answer 1

首先，您需要将movies 表与所有其他三个表连接起来，以找到任何电影的producer ,director and writer 的名称，并且 然后您可以过滤所有字段名称相同的结果。

作为旁注，永远不要使用旧样式的逗号分隔连接，始终使用正确的Inner Join 语法来连接两个或多个表

SELECT     movie_director.NAME 
FROM       movies m 
INNER JOIN movie_director md 
ON         m.movieid = md.movieid 
INNER JOIN movie_producer mp 
ON         m.movieid = mp.movieid movie_writer mw 
ON         m.movieid = mp.movieid 
WHERE      mp.NAME=md.NAME 
AND        mp.NAME=mw.NAME

Answer 2

你可以试试 group_concat。参考文档http://dev.mysql.com/doc/refman/5.0/en/group-by-functions.html#function_group-concat