Decomposing Barnes and Noble

Decomposing BJs Wholesale club

CJ MarselisMIS 2502

1Business RulesBJs is interested in developing a new application. The database will track product, customer, and sale information. It will also collect basic store information. The business rules are typical of most retail stores with the exception that sales are tracked to the customer since the customer is a member. The specific rules include:

A product may be supplied by multiple suppliersA manufacture produces many products but sells to clients through the supplierA sale to a store includes many productsA sale to a customer may include many productsThe sale to the customer includes the store number to facilitate returnsA store has only one managerAn employee can have only 1 position

A product may be supplied by multiple suppliersM:N relationship between Product and Suppliers

3A manufacture produces many products but sells to clients through the supplier

Lets consider the relationship between manufacturer and products firstWhile a product COULD be produced by many manufacturers, lets assume that this is not the case

A manufacture sells to clients through the supplierIn this case the client is the StoreBasically, we need a sale to show the purchase of the product from the manufacturer to the supplier BUT this is out of scope of this db. Since were building the DB for BJs and BJs wouldnt want to store the purchases of the products by the supplier from the manufacturer, we wont worry about this

A sale to a store from a supplier

Since BJs would want to know what products it ordered for each store from the suppliers, we need to house this information in our dbEssentially, this is just a sale!Remember all sales include the following components:CustomerSellerProductsGeneral Sale informationDetails about the sale

6SaleRemember all sales include the following components:SellerCustomerProductsSince the seller sells to multiple customers and a customer buys from multiple sellers, its a M:NEach time a customer buys stuff from a seller, its a sale Thats the bridge!In this case:Seller = Supplier Customer = StoreSale = delivery invoice

Delivery Invoice

The Delivery Invoice shows the M:N between Store and SupplierNeed FKs to Store and SupplierDeliver and order dateCould add employee that placed the order at the buyer. This will be FK to employee table

A sale to a store includes many products

The buyer can purchase many products in the sale. Since an invoice includes many products and a product can be sold in many invoices, its a M:N between an invoice and productNeed to show the FKs to the product and invoice tables

9The sale to the customer includes the store number to facilitate returns

Sale includes:Seller = StoreCustomer = CustomerSale = Sale

10Lets say we want to track which cashier rang up the sale. An employee can have only 1 position

Add cashier as FK to Employee Lookup

11A sale to a customer may include many products

Just like the invoice detail table, need a bridge between sale and products

12A store has only one manager

13Put it all together