Here we will work on exercise to break the table up till 3NF:
Original Table :
1NF
Making CustNo and PropNo as Primary Keys:
To make things easier , find functional dependencies , so it will make easier for us to break and understand the table :
We have three relations having the following functional dependencies:
– CustNo, PropNo -> RentStart, RentFinish
– CustNo -> CustName
– PropNo ->Paddress, Rent, OwnerName, Oname
As we see the functional dependencies , we can come up with the 2NF:
– Customer(CustNo, Cname)
– Rental(CustNo, PropNo, RentStart, RentFinish)
– Property_Owner(PropNo, Paddress, Rent, OwnerNo,OName).
2NF:
In 2NF, there the columns should not be dependent on partial or part of Primary Key.
3NF
No non-primary-key attributes that are transitively dependent on the primary key.
So, We have 4 relations:
• Customer(CustNo, Cname)
• Rental(CustNo, PropNo, RentStart,RentFinish)
• Property_For_Rent(PropNo, Paddress, Rent, OwnerNo)
• Owner(OwnerNo, OName)
SqlBird 