Question

Question 2

Consider the following six relations for an order-processing database applicationin 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)

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

Answer 1

Foreign Keys: Those attributes in a relation are known as foreign Keys that are the primary keys of another table.

1.

FOREIGN KEY ORDER(Cust#) REFERENCES CUSTOMER(Cust#)

i.e., Cust# attribute in table 'ORDER' is a foreign key that references table 'CUSTOMER'

2.

FOREIGN KEY ORDER_ITEM(Order#) REFERENCES ORDER(Order#)

3.

FOREIGN KEY ORDER_ITEM(Item#) REFERENCES ITEM(Item#)

4.

FOREIGN KEY SHIPMENT(Order#) REFERENCES ORDER(Order#)

5.

FOREIGN KEY SHIPMENT(Warehouse#) REFERENCES WAREHOUSE (Warehouse#)