SQL many to many select

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'

Select M.name
From   manufacturer M
Where  M.id_manufacturer in ( Select P.id_manufacturer
                              From   product P
                              Where  P.id_product in ( Select C.id_product
                                                       From   category_product C
                                                       Where  C.id_category = ?))

Query without joins will look like following :

SELECT m.name 
FROM manufacturer as m, product as p, category_product as cp 
WHERE cp.id_category = <your value>
      AND cp.id_product = p.id_product 
      AND p.id_manufacturer = m.id_manufacturer