[英]Select/Join from multiple tables where tbl1.x = tbl2.x = tbl3.x
我有一个电影数据库,需要执行查询以返回由同一人撰写,导演和制作的所有电影。
我在电影->制片人,电影->导演和电影->作家之间有很多联系,它们被称为movie_director,movie_producer和movie_writer。 这些表具有称为人员的表的外键和具有电影表的外键。
如何选择具有同一个制片人,导演和编剧的电影? 我已经试过这个select语句,但是它返回很多重复项:
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;
感谢所有帮助或有用信息的链接!
首先,您需要将movies
表与所有其他三个表连接起来,以查找任何电影的producer ,director and writer
的名称,然后可以在所有字段中名称相同的地方过滤结果。
另外请注意,请勿使用旧式逗号分隔的连接,请始终使用正确的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
您可以尝试group_concat。 参考文档http://dev.mysql.com/doc/refman/5.0/en/group-by-functions.html#function_group-concat
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