The main entities of a Credit Card Sales System are:
3. Order Details
The main relationships among entities of a credit card sales System are:
1. Customer places an order.
2. Order contains order details.
3. An Order detail has a product.
4. Bank completes the payment.
The main assumptions in a Credit Card Sale System are:
1. The Customer and the Retailer have an account in the same bank. 2. Instead of the grid through which all the banks are connected the payment is processed by the bank for simplicity.
Tables and Primary Keys
The three normalization forms are
1. First normal form
2. Second normal form
3. Third normal form
First normal form
First normal form states that there should be no repeating elements or groups of elements in any table of database. As we can see that every table has a primary key which is unique for every tuple in every table so we can’t have repeating elements or groups of elements in any table.
Second normal form
Second normal form states that there should be no partial dependencies on a concatenated key. As we can see that we don’t have any concatenated key in any table so there any partial dependency does not exist.
Third normal form
Third normal form states that there should be no dependencies on non-key attributes. As we can see that all the attributes of every table depends upon only primary key so there is no dependency of any attribute on non-key attributes.