6
Database Design
Procedures
Yong Choi
School of Business
CSUB
6
2
6
Phase 1: Database Initial Study
• Purposes
– Analyze company situation
• Operating environment
• Organizational structure
– Define problems and constraints
– Define objectives
– Define scope and boundaries
3
6
Initial Study Activities
4
6
Phase 2: Database Design
•
•
•
•
Most Critical DBLC phase
Makes sure final product meets requirements
Focus on data requirements
Subphases
–
–
–
–
Create conceptual design
DBMS software selection
Create logical design
Create physical design
5
6
Two Views of Data
6
6
I. Conceptual Design
• Data modeling creates abstract data structure to
represent real-world items
• High level of abstraction
• Four steps
–
–
–
–
Data analysis and requirements
Entity relationship modeling and normalization
Data model verification
Distributed database design
7
6
Data analysis and Requirements
• Focus on:
– Information needs:
• What output (reports and queries) must be
generated by the system? What information dose
the current system generate and to what extent is
that information adequate?
– Information users:
• Who will use the information? How is the
information to be used? What are the different enduser views?
8
6
Data analysis and Requirements
• Focus on:
– Information sources
• Where is the information to be found? How is the
information to be extracted once it is found?
– Information constitution:
• What data elements are needed to produce the
information? What are the data attributes? What
relationships exist among the data? What is the data
volume How frequently are the data used? What data
transformations are to be used to generate the required
information?
9
6
Data analysis and Requirements
• Data sources
– Developing and gathering end-user data views
– Direct observation of current system
– Interfacing with systems design group
• Draft business rules based on a Draft ER model
10
6
E-R Modeling is Iterative
11
6
Concept Design: Tools and Sources
12
6
Data Model Verification
• E-R model is verified against proposed system
processes
– End user views and required transactions
– Access paths, security, concurrency control
– Business-imposed data requirements and
constraints
• Reveals additional entity and attribute details
• Define major components as modules
– Cohesivity
– Coupling
13
6
E-R Model Verification Process
14
6
Iterative Process of Verification
15
6
DB Design Strategy Notes
• Top-down
– 1) Identify data sets
– 2) Define data elements
• Bottom-up
– 1) Identify data elements
– 2) Group them into data sets
16
6
Top-Down vs. Bottom-Up
17