Avoid duplicate entries when joining multiple tables (MySQL) - mysql

Question

(please see the database structure I'm testing with at the bottom of this post.)
I execute this query:
SELECT m.title, GROUP_CONCAT(DISTINCT(d.name) SEPARATOR ',') d FROM movies m
INNER JOIN movies_seen s
ON s.object_id = m.id
LEFT JOIN movies_directors_connections dc
ON dc.movie_id = m.id
LEFT JOIN movies_directors d
ON d.id = dc.director_id
With this result:
title | d
Pulp Fiction | Quentin Tarantino,George Butler,Robert Fiore
But I'm trying to get this:
title | d
Pulp Fiction | Quentin Tarantino
Pumping Iron | George Butler,Robert Fiore
And suggestions? :)
CREATE TABLE `movies` (
`id` int(10) unsigned NOT NULL AUTO_INCREMENT,
`title` varchar(90) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=3 ;
CREATE TABLE `movies_seen` (
`object_id` int(10) NOT NULL DEFAULT '0',
`date` varchar(10) NOT NULL DEFAULT '0');
CREATE TABLE `movies_directors` (
`id` mediumint(8) unsigned NOT NULL AUTO_INCREMENT,
`name` varchar(255) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=4 ;
CREATE TABLE IF NOT EXISTS `movies_directors_connections` (
`movie_id` mediumint(8) unsigned NOT NULL DEFAULT '0',
`director_id` mediumint(8) unsigned NOT NULL DEFAULT '0'
) ENGINE=MyISAM;
And then some test data:
INSERT INTO `movies` (`id`, `title`) VALUES
(1, 'Pulp Fiction'), (2, 'Pumping Iron');
INSERT INTO `movies_seen` (`object_id`, `date`) VALUES
(1, 1359511222), (2, 1359511223);
INSERT INTO `movies_directors` (`id`, `name`) VALUES
(1, 'Quentin Tarantino'),
(2, 'George Butler'),
(3, 'Robert Fiore');
INSERT INTO `movies_directors_connections` (`movie_id`, `director_id`) VALUES
(1, 1), (2, 2), (2, 3);

Answer 1

you just need to add GROUP BY clause
SELECT m.title,
GROUP_CONCAT(DISTINCT(d.name) SEPARATOR ',') d
FROM movies m
INNER JOIN movies_seen s
ON s.object_id = m.id
LEFT JOIN movies_directors_connections dc
ON dc.movie_id = m.id
LEFT JOIN movies_directors d
ON d.id = dc.director_id
GROUP BY m.title
SQLFiddle Demo
OTHER LINK
MySQL GROUP BY clause