1. CS 3630 Database Design and Implementation

2. Design Methodology Three main phases
A structured approach that uses procedures, techniques, tools, and documentation aids to support and facilitate the process of design.
Three main phases
Conceptual database design
Understanding client data
E-R (EER) Model
Contract between clients and designers
E-R Model could be used for any database system
Logical database design
Mapping E-R Model to (relational) database schema
Normalization
Physical database design
Go over Quiz1

3. How to maintain relationships?
Foreign Key
Primary key of another relation (table)
Representing relationship between two relations (tables)

4. Foreign Key: Examples
Branch (Bno, Street, City, State, Zipcode, Phone)
Staff (Sno, firstName, lastName, Address, Bno )
Owner (Ono, firstName, lastName, Phone (Multi-Value))
PropertyForRent (Pno, Street, City, State, Zipcode, Ono)
Client (Cno, firstName, lastName, Phone, MaxRent, PrefType)
Viewing (Cno, Pno, ViewDate, ViewTime, Comment)

5. How to Represent Relationship?
Primary Key and Foreign Key!
1:1
1:* (1..m)
*:* (m..n)
Complex relationship
Recursive relationship
Superclass / Subclass Relationship

6. One-to-Many (1:*) Owner (1) Owns (0..*) PropertyForRent
Parent entity: one side
Owner
Child entity: many side
PropertyForRent
Do we need a table for the relationship?
NO!
Copy PK of parent entity to child entity as FK
Copy Ono to PropertyForRent
Does it work to copy Pno to Owner?

7. Mapping Entities with Relationship to Table Schemas
E-R Model
Owner (Ono, firstName, lastName, Phone)
Property(Pno, Street, City, State, Zipcode, Rent)
Owner (1) Owns (0..*) Property
Table Schemas (DBDL)
PK: Ono
AK: None
FK: None
Property(Pno, Street, City, State, Zipcode, Rent, Ono)
PK: Pno
AK: Street, City, Zipcode
FK: Ono references Owner

8. Example E1 E2 A1 B1 A2 composite (A21, A22) B2: Multi-value B3
PK: A1 PK: B1
E1 (1..*) RelatedTo (1) E2
Table Schemas (DBDL)
E1 (A1, A21, A22, B1) E2 (B1, B3)
PK: A PK: B1
AK: None AK: None
FK: B1 references E FK: None
E3 (B1, B2, NewID)
PK: NewID
AK: None
FK: B1 references E2

9. Attributes of Relationships
E1 E2
A1 B1
A2 composite (A21, A22) B2: Multi-value B3
PK: A1 PK: B1
E1 (1..*) RelatedTo (1) E2
Attributes: C1, C2, C3
Which table should the attributes C1, C2, and C3 go?
Go with the FK!

10. Attributes of Relationships
E1 E2
A1 B1
A2 composite (A21, A22) B2: Multi-value B3
PK: A1 PK: B1
E1 (1..*) RelatedTo (1) E2
Attributes: C1, C2, C3
Table Schemas (DBDL)
E1 (A1, A21, A22, B1, C1, C2, C3) E2 (B1, B3)
PK: A PK: B1
AK: None AK: None
FK: B1 references E FK: None
E3 (B1, B2, NewID)
PK: NewID
AK: None
FK: B1 references E2

11. One-to-One (1:1)
Are the two entity types identical with different names?
Client Customer
Staff Employee
Can the two entity types be combined into one entity type?
Client (1) Provides (1) RegstrationInfo
Client (1) Has (1) Interview

12. One-to-One (1:1)
The two entity types are not identical, and cannot be combined into one entity.
Do we need a new table for the relationship?
NO!
Copy one PK as FK.
Which Direction: Three Cases
Total on both sides
Partial both sides
Total on one side and Partial on the other side
Don’t want to combine into one table: too many null values.

13. Many-to-Many (*:*) Entity1 (0..*) RelatedTo (1..*) Entity2
Will Coping PK as FK work?
NO!
No multi-value attributes!
What to do?
Adding a new table!

14. Many-to-Many (*:*) Client (0..*) Views (0..*) Property
(Date, Time, Comment)
New Table
Viewing
Attributes: Date, Time, Comment
New relationships
Client (1) Has (0..*) Viewing
Viewing (0..*) IsFor (1) Property
One (*:*) becomes two (1:*)
Copy PK of both Client and Property to Viewing as FK
Figure out PK or create a new ID attribute

15. Original Entities (E-R Model)
Example
Original Entities (E-R Model)
Property (Pno, Street, City, State, Zipcode, Ono)
Client (Cno, firstName, lastName, Phone, MaxRent, PrefType)
Client (0..*) Views (0..*) Property
(Date, Time, Comment)
Table Schemas (DBDL)
PK: Pno
AK: Street, City, State, Zipcode
FK: Ono references Owner (not from the *:* relationship)
PK: Cno
AK: None
FK: None
Viewing (Cno, Pno, ViewDate, ViewTime, Comment)
PK: Cno, ViewDate, ViewTime
FK: Cno references Client
Pno references Property
ViewDate has both date and time

16. Where to Store Attributes of Relationship
Staff (1) Interviews (0..*) Client
Attributes: date, time, comment
Staff (StaffNo, …)
PK: StaffNo
AK: None
FK: BranchNo references Branch
Client (ClientNo, Name, Address, . . .
InterviewStaffNo, InterviewDate, IntervieTime, InterviewResult)
PK: ClientNo
FK: InterviewStaffNo references Staff

17. Where to Store Attributes of Relationship
Staff (0..*) Inspects (0..*) Car
Attributes: date, time, fault
Staff (StaffNo, . . .)
Car (CarNo, . . .)
Inspection (ID, StaffNo, CarNo, Date, Time, Fault)
PK: ID
AK: CarNo, Date, Time
StaffNo, Date, Time
FK: StaffNo references Staff
CarNo references Car

18. Composite PK/FK E1 E2 A1: composite (A11, A12) B1 A2 B2
A3: composite (A31, A32, A33) B3: composite (B31, B32)
PK: A PK: B1, B2
E1 (0..1) RelatedTo (1..*) E2
Attributes: Att1, Att2
Copy A1 to E2 as FK
Copy (A11, A12) to E2 as FK!

19. Composite PK/FK E1 (A11, A12, A2, A31, A32, A33) PK: A11, A12 AK: None
E1 E2
A1: composite (A11, A12) B1
PK: A PK: B1, B2
E1 (0..1) RelatedTo (1..*) E2
Attributes: Att1, Att2
E1 (A11, A12, A2, A31, A32, A33)
PK: A11, A12
AK: None
FK: None
E2 (B1, B2, B31, B32, A11, A12, Att1, Att2)
PK: B1, B2
FK: (A11, A12) references E1

20. Complex Relationship (involving 3 or more entities)
Client REGESTERS with Staff at Branch
Add a new table Registration
Registers
Branch
Staff
Client

21. Complex Relationship Client REGESTERS with Staff at Branch
Add a new table Registration
1..1
0..*
0..*
1..1
Client
Registration
Branch
Staff
Has
CarryOut
1..1
Does
1..1
Is Client the same as Registration?

22. Recursive Relationship
One-to-Many (1:*)
Staff (0..1) Supervises (0..*) Staff
(Supervisor) (Supervisee)
Add a new column (SupervisorNo)
One-to-One (1:1)
Add a new column
Many-to-Many (*:*)
Add a new table

23. Superclass/subclass Relationship

24. Multiple Relationships between two Entities Staff and Branch
Branch (Bno, Street, City, State, Zipcode, Phone)
Staff (Sno, firstName, lastName, Address)
Branch (1) Has (1..*) Staff
Staff (1) Manages (0..1) Branch
Cannot have circular references.
Staff (Sno, firstName, lastName, Address, Bno, Position)

25. Mapping Weak Entities to Relation Schema
Primary Key may not exist
Adding PK based on the relationship
Combining weak entity into parent entity

26. Strong and Weak Entities
Staff (Sno, firstName, lastName, Address, Phone, Salary)
Next_Of_Kin(firstName, lastName, Address, Phone)
Staff (1..*) RelatedTo (0..1) Next_Of_Kin
attribute: relationship
This is a one-to-many relationship.
Create PK for Next_Of_Kin and copy that with attribute relationship to Staff as FK
Combine into one table Staff
Same person may be Next_Of_Kin of multiple staff members
Next_Of_Kin of different staff members are not related

27. Design Methodology Three main phases Conceptual database design
Understanding client data
E-R (EER) Model
Contract between clients and designers
E-R Model could be used for any database system
Logical database design
Mapping E-R Model to (relational) database schema
Normalization
Physical database design
Go over Quiz1

28. DBDL (Database Design Language)
Branch (Bno, Street, City, State, Zipcode, Phone)
PK: Bno
AK: Street, City, State, Zipcode
FK: None
Staff (Sno, firstName, lastName, Address, Bno )
PK: Sno
AK: None
FK: Bno references Branch
Client (Cno, firstName, lastName, Phone, MaxRent, PrefType)
PK: Cno
FK: None
Viewing (ID, Rno, Pno, ViewDate, ViewTime, Comment)
PK: ID
AK: Rno, ViewDate, ViewTime
Pno, ViewDate, ViewTime
FK: Rno references Client (Cno)
Pno references Property
No multi-value attributes, no composite attributes.
All relationships are maintained through FKs.
New attribute ID for Viewing.

29. Assignment4
Due Wednesday, by noon Class 1DropBox folder UserName_A4 (UserName_A4_2) No UserName_A4_3! No 0KB!