mysql alter table relationship cascade

Question

I have this piece of code to alter a tables relationship but I want to add cascade update and delete operations do I need to add cascade update cascade delete to this code

ALTER TABLE product_images
ADD FOREIGNKEY (product_id) REFERENCES products(product_id)

this is a one to many relationship I hope my code is right for a start. I have a products table and a product_images table which has many images for each product

Updated

ALTER TABLE product_images
ADD FOREIGN KEY (product_id) REFERENCES products(product_id)

Answer 1

Those referential actions need to be specified. RESTRICT is default.