Combinar resultados repetidos en columnas virtuales

[lambar]

Se me ha quedado así al final y funciona perfectamente, muchísimas gracias otra vez.

Código MySQL:

SELECT p.products_id, p.products_model, p.products_image, p.products_price, m.manufacturers_id, m.manufacturers_name, d.products_name, GROUP_CONCAT(CONCAT(c.categories_id, '-', c.categories_name)) as categorias
FROM products p
LEFT JOIN manufacturers m ON p.manufacturers_id = m.manufacturers_id
LEFT JOIN products_description d ON p.products_id = d.products_id
AND d.language_id =3
LEFT JOIN products_to_categories pc ON p.products_id = pc.products_id
LEFT JOIN categories_description c ON c.categories_id = pc.categories_id
AND c.language_id =3
GROUP BY  p.products_id