1. CS 3630 Database Design and Implementation

2. Unnormalized Form (UNF)
student courses
Joe Clifton CS3630
CS3340
CS3230
Multi-Value attribute
Common in reports
2NF and 3NF could be in one note.

3. First Normal Form (1NF) No multi-value attributes
Done when mapping E-R model to relational schema
DBDL

4. Second Normal Form (2NF)
A relation R is in 1NF, and
every non-primary-key attribute is fully functionally dependent on the primary key
Then R is in 2NF
No Partial FDs on the PK.

5. Partial FDs X, Y  W is a partial FD if X  W or Y  W is true
Lease (RNo, RName, PNo, PAddress, Start, Finish, Rent, ONo, OName)
PAddress, Start  All
PAddress, Start  PNo, ONo, OName
PAddress  PNo, ONo, OName

6. Second Normal Form (2NF)
No Partial FDs on the PK.
PK  All other attributes
Assume a table with a simple PK of Att1
Att1  All other attributes
Is it in 2NF?
Cannot have partial FD on simple PK
Assume a table with a composite PK of Att1 and Att2
Att1, Att2  Att3, Att4, Att5 (All other attributes)
It’s possible
Att2  Att5
Att1, Att2  Att3, Att4

7. Example
Lease (RNo, RName, PNo, PAddress, Start, Finish, Rent, ONo, OName)
PK: PNo, Start
AK: PNo, Finish
PAddress, Start
PAddress, Finish
FDs:
PNo, Start  All
PNo, Finish  All
PAddress, Start  All
PAddress, Finish  All
RNo  RName
ONo  Oname
PAddress  PNo, ONo, OName
PNo  PAddress, ONo, OName
Partial FD on Primary Key?

8. Table Instance Not in 2NF! Poor Performance Redundancy Inconsistency
RNo RName PNo PAddress Start Finish Rent Ono OName
R John P main O Tina
R Mike P main O Tina
R Kay P main O Tina
R John P main O Tony
R Scot P first O Tony
PNo, Start  All other attributes
(Partial on Primary Key)
PNo  PAddress, ONo, OName
Not in 2NF!
Poor Performance
Redundancy
Inconsistency
What to Do?
Move the attributes to another table!

9. Decompose Lease into 2NF
Lease (RNo, RName, PNo, PAddress, Start, Finish, Rent, ONo, OName)
PK: PNo, Start
Partial FD on Primary Key
PNo  PAddress, ONo, OName
Remove partial dependent on Primary Key
Create a new relation
Which attributes are in the new relation?
All attributes in the partial FD (both side of)
Lease1 (PNo, PAddress, ONo, OName)
Which attributes are left in the original relation?
PK remains the same
Lease (RNo, RName, PNo, Start, Finish, Rent)
PK?
FK?

10. Lease1 (PNo, PAddress, ONo, OName)
PK: PNo
AK: PAddress
FK: None (from this conversion)
Functional Dependencies:
PNo  All other attributes
PAddress  PNo, ONo, OName
ONo  OName
In 2NF?
Lease (RNo, RName, PNo, Start, Finish, Rent)
PK: PNo, Start
AK: PNo, Finish
FK: PNo references Lease1
Functional Dependencies:
PNo, Start  All other attributes
PNo, Finish  All other attributes
RNo  Rname
In 2NF?

11. Relation/Table Instances
Lease
Rno RName PNo PAddress Start Finish Rent Ono OName
R101 John P main O100 Tina
R102 Mike P main O100 Tina
R103 Kay P main O100 Tina
R101 John P main O110 Tony
R105 Scot P first O109 Tony
Lease1
PNo PAddress ONo OName
P main O Tina
P main O Tony
P first O Tony
PNo, PAddress, Ono, OName (Lease)

12. Removing Duplicates Lease1 PNo PAddress ONo OName
P main O Tina
P main O Tony
P first O Tony
P main O Tina
P main O Tony
P first O Tony

13. Lease (before) Lease (after) RNo RName PNo Start Finish Rent
RNo RName PNo PAddress Start Finish Rent Ono OName
R John P main O Tina
R Mike P main O Tina
R Kay P main O Tina
R John P main O Tony
R Scot P first O Tony
Lease (after)
RNo RName PNo Start Finish Rent
R John P
R Mike P
R Kay P
R John P
R Scot P
RNo, RName, RNo, Start, Finish, Rent (Lease)

14. Some FDs are lost
Lease (RNo, RName, PNo, PAddress, Start, Finish, Rent, ONo, OName)
PAddress, Start  All
PAddress, Finish  All
Lease1 (PNo, PAddress, ONo, OName)
Lease (RNo, RName, PNo, Start, Finish, Rent)

15. Assignment 5-1

16. Assumptions
Identify all non-trivial FDs
NIN  eName
contractNo  hNo, hLoc
hNo  hLoc
NIN, contractNo  All
( NIN, contractNo  hours)
Choose a PK:
NIN, contractNo
List all AKs:
NONE

17. Schedule
Assignment 61 Due Thursday, March 1, by 5 pm Quiz 2 Wednesday, March 7 Covers A4 and A51, A61

18. Assignment 4