Q1: Define the following terms as they apply to the relational model of data: super key, key, candidate key, primary key, and foreign key. Show the difference between them by giving examples.

Q2: Consider the following six relations for an order-processing database application in a company:

CUSTOMER (Cust#, Cname, City)

ORDER (Order#, Odate, Cust#, Ord_Amt)

ORDER_ITEM (Order#, Item#, Qty)

ITEM (Item#, Unit_price)

SHIPMENT (Order#, Warehouse#, Ship_date)

WAREHOUSE (Warehouse#, City)

Here, Ord_Amt refers to total dollar amount of an order; Odate is the date the order was placed; Ship_date is the date an order (or part of an order) is shipped from the warehouse. Assume that an order can be shipped from several warehouses. Specify the foreign keys for this schema, stating the referenced primary keys and any assumptions you make. What other constraints can you think of for this database?

Q3: Consider the following relations for a database that keeps track of business trips of salespersons in a sales office:

SALESPERSON (SSN, Name, Start_Year, Dept_No)

TRIP (SSN, From_City, To_City, Departure_Date, Return_Date, Trip_ID)

EXPENSE (Trip_ID, Account#, Amount)

Specify the foreign keys for this schema, stating the referenced primary keys and any assumptions you make.