6.e.    Consider a simple purchase made with a credit card. Many BANKs issue a credit cards to many of its CUSTOMERs. Naturally, each CUSTOMER may have credit cards from any number of BANKs. Each BANK has a unique BankID and other characteristics. Information maintained about a CUSTOMER includes the CustID, CustName, CustAddress, CreditLimit, and AvailableBalance. The CreditLimit is the maximum amount of credit available, and the AvailableBalance is equal to the CreditLimit minus the amount of the outstanding (made but not yet paid for) purchases made by the CUSTOMER. Additionally, each credit card transaction involves the MERCHANT (the store where the customer made the purchase). Information maintained about the MERCHANT includes the MerchantID, and other information. Therefore, each credit card transaction must include information about the CUSTOMER who made the purchase, The BANK that issued the credit card, and the MERCHANT who sold the item(s). Transaction Information must also include the date of the transaction, as well as the amount of the transaction (if an item is returned, the amount of the transaction is negative).

 

         Draw the ERD to reflect this situation.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

*  Primary Key

** Primary AND Foreign Key