1. Chapter 9 Part-1: Concepts & Foreign Keys
Database Design
Chapter 9
Part-1: Concepts & Foreign Keys

2. Outline Part One Data Management Dept Types of DBs
From Conceptual Data Model to a Database
Relational DB Model
Designing a Relational DB
Multi-valued Attributes
Representing Relationships
Referential Integrity

3. Different Focus Systems Analyst Data Administrator Requirements
Use Cases – the user must be able to:
Enter orders
Track order status
Enter/assign/resolve complaints
Data Model – the system must be able to capture:
Order #
Order Date
Customer Info
Billing address
Shipping address
Products, & quantity
Price, discounts
Systems Analyst
Data Administrator
Primary
responsibility
Assist to ensure
consistency
w/existing systems

4. Database Administrator (DBA)
Data Management Dept.
Data Administrator
Database Administrator (DBA)
Data Standards - Naming, etc
Data use - Ownership, accessibility
Data quality - Integrity rules
Managing the DBMS environment
Performance monitoring & tuning
Security
Backup & Recovery
Database

5. Types of Databases Types of Databases
Hierarchical
Network
Relational
Object-oriented
Relational Database Management System (RDBMS)
organizes data into tables (i.e. relations)
Tables are two dimensional data structures
Record – row or tuple
Field – column or attribute

6. From Conceptual Data Model to a Database
ERD
Domain Class Diagram
RDBMS
Entity
Class
Table
Attribute
Field
Instance
Object
Record
Primary Key
Identifier
Relationship
Association
Foreign Key
Cardinality
Multiplicity **
** Relationship rules –will learn in the DB class

7. Relational Database Model
(def) a model where data is represented as a set of related tables or relations.
Properties/Rules of Relations:
Entries in cells are simple. (Rule of Atomic Values)
Entries in columns are from the same set of values. (Domain)
Each row is unique. (Primary Key)
Order of columns may be interchanged
Order of rows may be interchanged
Other Rules come from “Normalization”

8. Designing a Relational DB
Topic
Description
Tables
Create TBs – 1 for each entity/domain class
Primary Keys
Select/define a PK for each TB
Associative
Create new tables to represent many-to-many relationships
Multi-Valued Attributes
Resolve to new tables
Foreign Keys
Add FKs to establish relationships
Super & Sub Classes
Decide on how to represent any Generalization Hierarchies
Referential Integrity
Define Referential Integrity constraints
Normalization
Evaluate schema quality and make necessary improvements
Data Types
Determine appropriate data types for validation, integrity   

9. Multi-Valued Attributes
No Multi-Valued Attributes
 Due to the Rule of Atomic Values
Employee
EmpID {key}
lastName
firstName
title
dependents
Employee Table
EmpID
LastName
FirstName
Title
Dependents
111
Smith
Robert
Accountant
Bobbie, Sue
222
Jones
Leo
Programmer
333
Lopez
Trent
Sales Rep
Trent Jr, Trevor, Sue
Dependents Table
EmpID
Dependents
111
Bobbie
Sue
333
Trent Jr
Trevor
PK?
Employee Table
EmpID
LastName
FirstName
Title
111
Smith
Robert
Accountant
222
Jones
Leo
Programmer
333
Lopez
Trent
Sales Rep

10. Foreign Keys: Establishing Relationships
One to Many Relationship
create foreign key in the relation that is on the “many” side of relationship only
NOTE: Going the other way would generate a multi-value attribute PK FK
Add DeptCd here
Copy it over
Department
deptCd {key}
deptName
location
Employee
EmpID {key}
lastName
firstName
title 1
employs *

11. Foreign Keys: Establishing Relationships
One to One Relationship
create foreign key in either relation
NOTE: IF you have one & only one on both sides, these may be merged into a single table PK FK
Copy it over
Add SSN here
Employee
EmpID {key}
lastName
firstName
title
ParkingSpace
psNo {key}
level
Accessible? 1
is assigned 1 PK FK
Copy it over
Add psNo here

12. Foreign Keys: Establishing Relationships
Many to Many Relationship
should’ve been eliminated on ERD!!!
create new relation with PKs of related entities as:
1 concatenated PK, and 2 FKs
Employee
Project
1..*
0..*
EmpProject PK FK
Copy it over PK FK
Copy it over
Employee
EmpID {key}
lastName
firstName
title
Project
projCd {key}
projName
desc
stDate
endDate
EmpProject
__________
role
stDate
1..1
0..*
1..*
1..1
(PK)

13. Super & Sub Classes 2 Options to Implement Separate Tables One Table
Student (SID, name, birthDate)
UndergradStudent (SID, mentor)
GradStudent (SID, thesisTopic)
One Table
Student (SID, name, birthDate, mentor, thesisTopic, studentType)
Student
Undergrad Student
Grad Student
SID {key} name
birthDate
mentor
thesisTopic

14. Referential Integrity
(def) an integrity constraint on the Foreign Key:
Prevents adding a FK value, if an associated PK value does not exist.
Prevents delete of PK value, if an associated FK value exists.
Prevents change of PK value, if an associated FK value exists.
Can override:
Cascade Delete  Overrides constraint #2
Cascade Update  Overrides constraint #3