many-to-many

category_product --------------- id_category id_product product --------------- id_product id_manufacturer manufacturer --------------- id_manufacturer name How would I create an SQL query so that it selects all the names from manufacturer when id_category is equal to something? It's a straightforward inner join of the tables: SELECT m.name, cp.id_category FROM manufacturer as m INNER JOIN product as p ON m.id_manufacturer = p.id_manufacturer INNER JOIN category_product as cp ON p.id_product = cp.id_product WHERE cp.id_category = 'some value' Query without joins will look like following :

I found the following table structures while I was watching ruby on rails tutorial. table actors id int 11 primary key auto_increment name varchar 30 table movies id int 11 primary key auto_increment name varchar 30 table actors_movies actor_id int 11 movie_id int 11 How do I make a query to select movies that an actor is involved in? I am not asking for ruby on rails code. I want the actual mysql query string. Thank you! one thing to consider is that you are going to load the author object (because of RoR models), so with the ID would be enough: select movies.id, movies.name from movies inner

I use Loggable behavioral extension to log changes in my entities. I want to log changes in manyToMany relations too. I want to show to user this kind of change log: +--------------------------------------------------+ | Article "My Article" change log: | +-------+------------+-----------------------------+ | Who | When | What | +-------+------------+-----------------------------+ | Admin | 2015-07-01 | Removed tags "tag1", "tag2" | | Admin | 2015-07-01 | Added tags "tag3" | +-------+------------+-----------------------------+ Event problem I think, Doctrine doesn't fire events when manyToMany

I have three tables: categories, languages and categories_languages. Categories_languages is many to many table which links together categories and languages. I would like to update a foregin key value in table languages but it throws me error #1451 - Cannot delete or update a parent row: a foreign key constraint fails! CREATE TABLE IF NOT EXISTS `categories` ( `id` int(11) unsigned NOT NULL auto_increment, `name` varchar(20) NOT NULL, `modified` int(10) unsigned NOT NULL, PRIMARY KEY (`id`), ) ENGINE=InnoDB DEFAULT CHARSET=utf8; CREATE TABLE IF NOT EXISTS `languages` ( `id` char(2) NOT NULL,

Foo has: @ManyToMany(mappedBy = "foos") private Set<Bar> bars and Bar has : @ManyToMany private Set<Foo> foos What difference does the location of mappedBy attribute make to a bi-directional relationship , other than whether table is called foo_bar, or bar_foo; and without the mappedBy attribute I get two join tables, both foo_bar and bar_foo. JB Nizet The documentation says: If the association is bidirectional, one side has to be the owner and one side has to be the inverse end (ie. it will be ignored when updating the relationship values in the association table): So, the side which has the