er diagram for supermarket billing system

Category management is a retailing and purchasing concept in which the range of products purchased by a business organization or sold by a retailer is broken down into discrete groups of similar or related products; these groups are known as product categories (examples of grocery categories might be: tinned fish, washing detergent, toothpastes). It is a systematic, disciplined approach to managing a product category as a strategic business unit.[1] The phrase "category management" was coined by Brian F. Harris.