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  • MySQL Multiple Table Join

    - by hitman001
    I have a 3 tables that I'm trying to join and get distinct results. CREATE TABLE `car` ( `id` int(10) unsigned NOT NULL AUTO_INCREMENT, `name` varchar(255) NOT NULL DEFAULT '', PRIMARY KEY (`id`) ) ENGINE=InnoDB mysql> select * from car; +----+-------+ | id | name | +----+-------+ | 1 | acura | +----+-------+ CREATE TABLE `tires` ( `id` int(10) unsigned NOT NULL AUTO_INCREMENT, `tire_desc` varchar(255) DEFAULT NULL, `car_id` int(10) unsigned NOT NULL, PRIMARY KEY (`id`), KEY `new_fk_constraint` (`car_id`), CONSTRAINT `new_fk_constraint` FOREIGN KEY (`car_id`) REFERENCES `car` (`id`) ON DELETE CASCADE ON UPDATE CASCADE ) ENGINE=InnoDB mysql> select * from tires; +----+-------------+--------+ | id | tire_desc | car_id | +----+-------------+--------+ | 1 | front_right | 1 | | 2 | front_left | 1 | +----+-------------+--------+ CREATE TABLE `lights` ( `id` int(10) unsigned NOT NULL AUTO_INCREMENT, `lights_desc` varchar(255) NOT NULL, `car_id` int(10) unsigned NOT NULL, PRIMARY KEY (`id`), KEY `new1_fk_constraint` (`car_id`), CONSTRAINT `new1_fk_constraint` FOREIGN KEY (`car_id`) REFERENCES `car` (`id`) ON DELETE CASCADE ON UPDATE CASCADE ) ENGINE=InnoDB mysql> select * from lights; +----+-------------+--------+ | id | lights_desc | car_id | +----+-------------+--------+ | 1 | right_light | 1 | | 2 | left_light | 1 | +----+-------------+--------+ Here is my query. mysql> SELECT name, group_concat(tire_desc), group_concat(lights_desc) FROM car left join tires on car.id = tires.car_id left join lights on car.id = car_id group by car.id; +-------+-----------------------------------------------+-----------------------------------------------+ | name | group_concat(tire_desc) | group_concat(lights_desc) | +-------+-----------------------------------------------+-----------------------------------------------+ | acura | front_right,front_right,front_left,front_left | right_light,left_light,right_light,left_light | +-------+-----------------------------------------------+-----------------------------------------------+ I get duplicate entires and this is what I would like to get. +-------+-----------------------------------------------+--------------------------------+ | name | group_concat(tire_desc) | group_concat(lights_desc) | +-------+-----------------------------------------------+--------------------------------+ | acura | front_right,front_left | right_light,left_light | +-------+-----------------------------------------------+--------------------------------+ I cannot use distinct in group_concat because I might have legitimate duplicates which I would like to keep. Is there any way to do this query using joins and not using inner selects like the statement below? SELECT name, (select group_concat(tire_desc) from tires where car.id = tires.car_id), (select group_concat(lights_desc) from lights where car.id = lights.car_id) FROM car Also, if I will use inner selects, will there be any performance issues over joins?

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