36782-vm/db/migrations/021_create_product_relations_table.sql

CREATE TABLE IF NOT EXISTS product_relations (
    product_id INT NOT NULL,
    related_product_id INT NOT NULL,
    PRIMARY KEY (product_id, related_product_id),
    FOREIGN KEY (product_id) REFERENCES products(id) ON DELETE CASCADE,
    FOREIGN KEY (related_product_id) REFERENCES products(id) ON DELETE CASCADE
);