The following data elements comprise the conceptual-level schema for a database:
Billing address
Cost
Credit limit
Customer name
Customer number
Description
Invoice number
Item number
Price
Quantity on hand
Quantity sold
Shipping address
Terms

Required
a. Identify three potential users and design a subschema for each. Justify your design by explaining why each user needs access to the subschema data elements.
b. Use Microsoft Access or some other relational database product to create the schema tables. Specify the primary key(s), foreign key(s), and other data for each table. Test your model by entering sample data in each table.