I am building a ecommerce application for my university project. In my project every product will belong to a category and child category(optional) and grand child category(optional). e.g product apple will belong to fresh-fruit which will belong to fruits & vegetables which will also belong to food category. Here food will be parent cat, fruits and vegetables will be child cat, fresh-fruit will be grand child cat. How can I implement the idea in the categories table where I can upload a product which will touch these fields?