CREATE TABLE mangas_categories(
    _id INTEGER NOT NULL PRIMARY KEY,
    manga_id INTEGER NOT NULL,
    category_id INTEGER NOT NULL,
    FOREIGN KEY(category_id) REFERENCES categories (_id)
    ON DELETE CASCADE,
    FOREIGN KEY(manga_id) REFERENCES mangas (_id)
    ON DELETE CASCADE
);

insert:
INSERT INTO mangas_categories(manga_id, category_id)
VALUES (:mangaId, :categoryId);

deleteMangaCategoryByMangaId:
DELETE FROM mangas_categories
WHERE manga_id = :mangaId;