1. Application Extension 5a
Part 2: Using Information Technology
Application Extension 5a
Database Design
Experiencing MIS, Fourth Canadian Edition
Copyright © 2016 Pearson Canada Inc.

2. Study Questions Who will volunteer?
How are database application systems developed?
What are the components of the entity-relationship data model?
How is a data model transformed into a database design?
What is the user’s role?
Who will volunteer? (Continued)
Q1 Who will volunteer?
Q2 How are database application systems developed?
Q3 What are the components of the entity-relationship data model?
Q4 How is a data model transformed into a database design?
Q5 What is the users’ role?
Q6 Who will volunteer? (continued)

3. Who will volunteer? Fundraising manager needs database to:
Find volunteers
Track volunteers
how many years
effectiveness
personal information
Q1 Who will volunteer?

4. How are database application systems developed?
Database application system consists of:
Database
DBMS
One or more database applications
Database application consists of:
Forms
Reports
Queries
Application programs
Q2 How are database application systems developed?

5. Database Development Process
Q2 How are database application systems developed?
Figure AE5a-1 Database Development Process

6. Database Application System Development Process
Developers interview users
Develop requirements for new system
Analyze existing reports, forms, and user activities
Requirements summarized in data model
Logical representation of structure of data
Contains description of data and relationships
Users validate and approve the data model
Design implemented in a database
Database filled with user data
Q2 How are database application systems developed?

7. Database Must include all data necessary for users to perform jobs
Contains only that amount of data, and no more
Developers rely on users to:
Tell them what to include
Check data model
Verify correctness and completeness
Q2 How are database application systems developed?

8. What are the components of the entity-relationship data model?
Techniques for creating data model
Entity-relationship (E-R) data model
Unified Modeling Language (UML)
E-R data model components
Entities (things) stored in the database
Relationships among those entities
Q3 What are the components of the entity-relationship data model?

9. Entities Some thing that users want to track May be:
e.g., Order, Customer, Salesperson, and Item
May be:
Physical object (e.g., Item or Salesperson)
Logical construct or transaction (e.g., Order or Contract)
Entity names are always singular
Entities have:
Attributes - describe characteristics of the entity
Identifier - attribute (or group of attributes) whose value is associated with one and only one entity instance
Q3 What are the components of the entity-relationship data model?

10. Student Data Model Entities
Q3 What are the components of the entity-relationship data model?
AE5a-2 Student Data Model Entities

11. Relationships Entities have relationships to each other
Single entity to single entity
1:N relationship
One-to-many
Single entity to many entities
N:M
Many-to-many
Q3 What are the components of the entity-relationship data model?

12. Example of Department, Adviser, and Student Entities and Relationships
Q3 What are the components of the entity-relationship data model?
AE5a-3 Example of Department, Adviser, and Student Entities and Relationships

13. E-R Diagrams Rectangles represent entities
Relationships shown by lines
Crow’s foot
Forks at end of lines
Indicate more than one relationship
Read “many”
Vertical line means at least one entity of that type
Small oval means entity is optional
Q3 What are the components of the entity-relationship data model?

14. Cardinality Number of entities that can be involved in relationship
Maximum cardinality
maximum number involved
Minimum cardinality
constraints on minimum requirements
Q3 What are the components of the entity-relationship data model?

15. Example of Relationships Showing Both Maximum and Minimum Cardinalities
Q3 What are the components of the entity-relationship data model?
Figure AE5a-6 Example of Relationships Showing Both Maximum and Minimum Cardinalities

16. How is a data model transformed into a database design?
Database design is the process of converting a data model into tables, relationships, and data constraints
Transforms entities into tables
Expresses relationships
defines foreign keys
Shows data constraints
Q4 How is a data model transformed into a database design?

17. Normalization
Normalization is the process of converting poorly structured tables into two or more well-structured tables
Data integrity problems
Different names for the same entity
Produces incorrect and inconsistent information
Resolve by eliminating duplicated data
Normalizing for Data Integrity
Eliminate data duplication
Slower to process
Construct tables such that every table has single topic
Q4 How is a data model transformed into a database design?

18. Representing Relationships
Q4 How is a data model transformed into a database design?
Figure AE5a-9 Transforming a Data Model into a Database Design

19. Representing a 1:N Relationship
Q4 How is a data model transformed into a database design?
Figure AE5a-10 Representing a 1:N Relationship

20. Relational Database Design
Designer creates table for every entity
Entity identifier becomes primary key of table
Attributes of entity become columns
Tables normalized to single theme
Represent relationships between tables
Add foreign key to one or more tables
Q4 How is a data model transformed into a database design?

21. What is the users’ role? Final judges as to what data should contain
Determine how records are related to each other
Need to review data model
Must insure that model reflects an accurate view of business
Q5 What is the Users’ Role?

22. Who will volunteer? (Continued)
Consultant creates data model
Based on interviews with users
Data model reviewed and approved
Database tables constructed
Primary and foreign keys selected
based on interviews
Microsoft Access database created
Relationships indicated
Forms and reports constructed
Q6 Who will volunteer (continued)?

23. Data Model for Volunteer Database
Q6 Who will volunteer (continued)?
Figure AE5a-12 Data Model for Volunteer Database

24. Active Review Q1 Who Will Volunteer?
Summarize the problem that the fund-raising manager must solve. Explain how a database can help solve this problem. Describe the missing information. In your own words, what data must be available to construct the missing information?

25. Active Review Q2 How are Database Application Systems Developed?
Name and briefly describe the components of a database application system. Explain the difference between a database application system and a database application program. Using Figure AE5a-1 as a guide, describe the major steps in the process of developing a database application system. Explain what role is crucial for users and why that role is so important.

26. Active Review
Q3 What are the Components of the Entity-Relationship Data Model?
Define the terms entity, attributes , and relationship. Give an example of two entities (other than those in this book) that have a 1:N relationship. Give an example of two entities that have an N:M relationship. Explain the difference between maximum and minimum cardinality. Show two entities having a 1:N relationship in which one is required and one is optional.

27. Active Review
Q4 How is a Data Model Transformed into a Database Design?
Give an example of a data integrity problem. Describe, in general terms, the process of normalization. Explain how normalizing data prevents data integrity problems. Explain the disadvantage of normalized data. Using your examples from Q3, show how 1:N relationships are expressed in relational database designs. Show how N:M relationships are expressed in relational database designs.

28. Active Review Q5 What is the Users’ Role?
Describe the major role for users in the development of a database application system. Explain what is required to change a 1:N relationship to an N:M relationship during the data modeling stage. Explain what is required to make that same change after the database application system has been constructed. Describe how this knowledge impacts your behaviour when a database application system is being constructed for your use.

29. Active Review Q6 Who Will Volunteer? (Continued)
Examine Figure AE5a-12 . Describe the maximum and minimum cardinality for each relationship. Justify these cardinalities. Change the relationship between Prospect and Phone to N:M, and explain what this means. Change the relationship between Prospect and Work to 1:1, and explain what this means. Explain how each relationship is represented in the design in Figure AE5a-14 . Show examples of both primary keys and foreign keys in this figure. In Contact , determine whether EmployeeName is part of a primary key or part of a foreign key. Explain what problem the consultant foresaw in the use of the Name attribute. Explain how that problem was avoided. The consultant added an attribute to the data model that was not part of the users’ world. Explain why that attribute will not add unnecessary complication to the users’ work experiences.