Lookup table in MySQL - mysql

Question

I'm doing my first work in PHP/MySQL & I need help. I have one master table:
CREATE TABLE `m4l_movies` (
`ID` int(11) NOT NULL AUTO_INCREMENT,
`Title` varchar(250) NOT NULL,
`Rating` int(11) NOT NULL,
`Genre` varchar(250) NOT NULL,
`Actors` varchar(250) NOT NULL,
`UserID` int(11) NOT NULL DEFAULT '1',
PRIMARY KEY (`ID`)
) ENGINE=MyISAM AUTO_INCREMENT=115 DEFAULT CHARSET=utf8;
that receives input for a form which has values from a these lookup tables:
CREATE TABLE `m4l_actors` (
`ID` int(11) NOT NULL AUTO_INCREMENT,
`Actor` varchar(255) NOT NULL,
PRIMARY KEY (`ID`)
) ENGINE=InnoDB AUTO_INCREMENT=232 DEFAULT CHARSET=utf8;
CREATE TABLE `m4l_genre` (
`ID` int(11) NOT NULL AUTO_INCREMENT,
`Genre` varchar(255) NOT NULL,
PRIMARY KEY (`ID`)
) ENGINE=InnoDB AUTO_INCREMENT=202 DEFAULT CHARSET=utf8;
CREATE TABLE `m4l_movierating` (
`ID` int(11) NOT NULL AUTO_INCREMENT,
`Movie_Rating` varchar(250) NOT NULL,
PRIMARY KEY (`ID`)
) ENGINE=MyISAM AUTO_INCREMENT=12 DEFAULT CHARSET=utf8;
& I've created a View:
SELECT m4l_movies.ID AS ID,
m4l_movies.Title AS Title,
m4l_movierating.Movie_Rating AS Rating,
m4l_movies.Actors AS Actors,
m4l_movies.Genre AS Genre
FROM m4l_movies
JOIN m4l_movierating ON m4l_movierating.ID = m4l_movies.Rating
INNER JOIN m4l_genre ON m4l_movies.Genre = m4l_genre.ID
INNER JOIN m4l_actors ON m4l_movies.Actors = m4l_actors.ID
ORDER BY m4l_movies.Title
Here is the out put I get:
----------------------------------------------------------------|
ID Title Rating Actor Genre |
10 Summer G (10,15,25) (45,115,123) |
1 About You G-1 (63,163,405) (3,16,51) |
5 Dog Years P (45,65,95) (98,163,357) |
----------------------------------------------------------------|
Firstly this view should return more than 200 records. Secondly, I need to know how to either create a lookup or some other method to convert the NAME & GENRE back to their corresponding text values. Some how the RATING value is doing it right but I can't get NAME or GENRE to do it correctly. I'm sure it has to do with either the way I've joined the tables but I can't figure out where I'm going wrong. Will someone PLEASE help me.
Ok trying to follow along with suggesting made by Phil I've removed actors, genre from movies tale & created movies_genre & movies_actors
DROP TABLE IF EXISTS `m4l_movies`;
CREATE TABLE `m4l_movies` (
`ID` int(11) NOT NULL auto_increment,
`Title` varchar(250) NOT NULL,
`Year` float NOT NULL,
`Review` varchar(250) NOT NULL,
`Rating` int(11) NOT NULL,
`Image` varchar(250) NOT NULL,
`Storyline` longtext NOT NULL,
`Director` varchar(250) NOT NULL,
`UserID` int(11) NOT NULL default '1',
PRIMARY KEY (`ID`)
) ENGINE=MyISAM AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;
CREATE TABLE `m4l_movie_actor` (
movie_id INT(11),
actor_id INT(11),
PRIMARY KEY (movie_id, actor_id),
FOREIGN KEY (movie_id) REFERENCES m4l_movies (ID),
FOREIGN KEY (actor_id) REFERENCES m4l_actors (ID)
);
CREATE TABLE `m4l_movie_genre` (
movie_id INT(11),
genre_id INT(11),
PRIMARY KEY (movie_id, genre_id),
FOREIGN KEY (movie_id) REFERENCES m4l_movies (ID),
FOREIGN KEY (genre_id) REFERENCES m4l_genre (ID)
);
DROP TABLE IF EXISTS m4l_genre;
CREATE TABLE m4l_genre (
ID int(11) NOT NULL auto_increment,
Genre varchar(250) NOT NULL,
PRIMARY KEY (ID)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;
DROP TABLE IF EXISTS m4l_actors;
CREATE TABLE m4l_actors (
ID int(11) NOT NULL auto_increment,
Actor varchar(255) NOT NULL,
PRIMARY KEY (ID)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;
but when I try to create the movie_actor OR movie_genre I get
09:29:45
CREATE TABLE `m4l_movie_actor` (movie_id INT(11), actor_id INT(11),
PRIMARY KEY (movie_id, actor_id),
FOREIGN KEY (movie_id) REFERENCES m4l_movies (ID),
FOREIGN KEY (actor_id) REFERENCES m4l_actors (ID) )
Error Code: 1215. Cannot add foreign key constraint
0.000 sec
09:40:56 CREATE TABLE m4l_movie_genre (movie_id INT(11),genre_id INT(11),
PRIMARY KEY (movie_id, genre_id),
FOREIGN KEY (movie_id) REFERENCES m4l_movies (ID),
FOREIGN KEY (genre_id) REFERENCES m4l_genre (ID) )
Error Code: 1215. Cannot add foreign key constraint
0.016 sec
From what I can gather this only occurs when you have data types mismatch, but I THINK I have all INT data types so why am I getting this error?

Answer 1

You appear to have made the classic blunder of storing relational data in an un-relatable way.
You should be using junction tables instead of comma separated values. For example...
CREATE TABLE `m4l_movies` (
`ID` int(11) NOT NULL AUTO_INCREMENT,
`Title` varchar(250) NOT NULL,
`Rating` int(11) NOT NULL,
-- removed Actors and Genre
`UserID` int(11) NOT NULL DEFAULT '1',
PRIMARY KEY (`ID`)
);
CREATE TABLE `m4l_movie_actor` (
movie_id INT(11) NOT NULL,
actor_id INT(11) NOT NULL,
PRIMARY KEY (movie_id, actor_id),
FOREIGN KEY (movie_id) REFERENCES m4l_movies (ID),
FOREIGN KEY (actor_id) REFERENCES m4l_actors (ID)
);
-- repeat for genres
You can then join on the junction table and on to the Actors / Genres tables, eg
SELECT ... m4l_actors.Actor ...
FROM m4l_movies
INNER JOIN m4l_movie_actor ON m4l_movies.ID = m4l_movie_actor.movie_id
INNER JOIN m4l_actors ON m4l_movie_actor.actor_id = m4l_actors.ID
If you want the result in a comma separated list, look into GROUP_CONCAT()