1. Systems Analysis and Design 9th Edition
Chapter 9
Data Design

2. Chapter Objectives
Explain file-oriented systems and how they differ from database management systems
Explain data design terminology, including entities, fields, common fields, records, files, tables, and key fields
Describe data relationships, draw an entity relationship diagram, define cardinality, and use cardinality notation
Explain the concept of normalization

3. Chapter Objectives
Explain the importance of codes and describe various coding schemes
Explain data warehousing and data mining
Differentiate between logical and physical storage and records
Explain data control measures

4. Introduction
Begins with a review of data design concepts and terminology, then discusses file-based systems and database systems, including Web-based databases
Concludes with a discussion of data storage and access, including strategic tools such as data warehousing and data mining, physical design issues, logical and physical records, data storage formats, and data controls

5. Data Design Concepts Data Structures
Each file or table contains data about people, places, things or events that interact with the information system
File-oriented system
Database management system (DBMS)

6. Data Design Concepts Overview of File Processing
File processing can be efficient and cost-effective in certain situations
Potential problems
Data redundancy
Data integrity
Rigid data structure

7. Data Design Concepts Overview of File Processing
Various types of files
Master file
Table file
Transaction file
Work file
Security file
History file

8. Data Design Concepts
The Evolution from File Systems to Database Systems
A database management system (DBMS) is a collection of tools, features, and interfaces that enables users to add, update, manage, access, and analyze the contents of a database
The main advantage of a DBMS is that it offers timely, interactive, and flexible data access

9. Data Design Concepts
The Evolution from File Systems to Database Systems
Some Advantages
Scalability
Better support for client/server systems
Economy of scale
Flexible data sharing
Enterprise-wide application – database administrator (DBA)
Stronger standards

10. DBMS Components
Interfaces for Users, Database Administrators, and Related Systems
Users
Query language
Query by example (QBE)
SQL (structured query language)
Database Administrators
A DBA is responsible for DBMS management and support

11. DBMS Components
Interfaces for Users, Database Administrators, and Related Systems
Related information systems
A DBMS can support several related information systems that provide input to, and require specific data from, the DBMS
No human intervention is required for two-way communication

12. DBMS Components Data Manipulation Language Schema
A data manipulation language (DML) controls database operations, including storing, retrieving, updating, and deleting data
Schema
The complete definition of a database, including descriptions of all fields, tables, and relationships, is called a schema
You also can define one or more subschemas

13. DBMS Components Physical Data Repository
The data dictionary is transformed into a physical data repository, which also contains the schema and subschemas
The physical repository might be centralized, or distributed at several locations
ODBC – open database connectivity
JDBC – Java database connectivity

14. Web-Based Database Design
Characteristics of Web-Based Design

15. Web-Based Database Design
Internet Terminology
Web browser
Web page
HTML (Hypertext Markup Language)
Tags
Web server
Web site

16. Web-Based Database Design
Internet Terminology
Intranet
Extranet
Protocols
Web-centric
Clients
Servers

17. Web-Based Database Design
Connecting a Database to the Web
Database must be connected to the Internet or intranet
Middleware
Adobe ColdFusion
Data Security
Well-designed systems provide security at three levels: the database itself, the Web server, and the telecommunication links that connect the components of the system

18. Data Design Terminology
Definitions
Entity
Table or file
Field
Record
Tuple

19. Data Design Terminology
Key Fields
Primary key
Candidate key
Foreign key
Secondary key

20. Data Design Terminology
Referential Integrity
Validity checks can help avoid data input errors
In a relational database, referential integrity means that a foreign key value cannot be entered in one table unless it matches an existing primary key in another table
Orphan

21. Entity-Relationship Diagrams
Drawing an ERD
The first step is to list the entities that you identified during the fact-finding process and to consider the nature of the relationships that link them
A popular method is to represent entities as rectangles and relationships as diamond shapes

22. Entity-Relationship Diagrams
Types of Relationships
Three types of relationships can exist between entities
One-to-one relationship (1:1)
One-to-many relationship (1:M)
Many-to-many relationship (M:N)

23. Entity-Relationship Diagrams
Cardinality
Cardinality notation
Crow’s foot notation
Unified Modeling Language (UML)
Now that you understand database elements and their relationships, you can start designing tables

24. Normalization Standard Notation Format
Designing tables is easier if you use a standard notation format to show a table’s structure, fields, and primary key
Example: NAME (FIELD 1, FIELD 2, FIELD 3)

25. Normalization Repeating Groups and Unnormalized Design
Often occur in manual documents prepared by users
Unnormalized
Enclose the repeating group of fields within a second set of parentheses

26. Normalization First Normal Form
A table is in first normal form (1NF) if it does not contain a repeating group
To convert, you must expand the table’s primary key to include the primary key of the repeating group

27. Normalization Second Normal Form
A table design is in second normal form (2NF) if it is in 1NF and if all fields that are not part of the primary key are functionally dependent on the entire primary key
A standard process exists for converting a table from 1NF to 2NF
The objective is to break the original table into two or more new tables and reassign the fields so that each nonkey field will depend on the entire primary key in its table

28. Normalization Third Normal Form
3NF design avoids redundancy and data integrity problems that still can exist in 2NF designs
A table design is in third normal form (3NF) if it is in 2NF and if no nonkey field is dependent on another nonkey field
To convert the table to 3NF, you must remove all fields from the 2NF table that depend on another nonkey field and place them in a new table that uses the nonkey field as a primary key

29. Normalization
A Normalization Example

30. Using Codes During Data Design
Overview of Codes
Because codes often are used to represent data, you encounter them constantly in your everyday life
They save storage space and costs, reduce data transmission time, and decrease data entry time
Can reduce data input errors

31. Using Codes During Data Design
Types of Codes
Sequence codes
Block sequence codes
Alphabetic codes
Significant digit codes
Derivation codes
Cipher codes
Action codes

32. Using Codes During Data Design
Developing a Code
Keep codes concise
Allow for expansion
Keep codes stable
Make codes unique
Use sortable codes

33. Using Codes During Data Design
Developing a Code
Avoid confusing codes
Make codes meaningful
Use a code for a single purpose
Keep codes consistent

34. Database Design: One Step At a Time
Create an initial ERD
Next, create an ERD
Review all the data elements
Review the 3NF designs for all tables
Double-check all data dictionary entries
After creating your final ERD and normalized table designs, you can transform them into a database

35. Database Models A Real-World Business Example
Imagine a company that provides on-site service for electronic equipment, including parts and labor

36. Database Models Working with a Relational Database
To understand the power and flexibility of a relational database, try the following exercise
Suppose you work in IT, and the sales team needs answers to three specific questions
The data might be stored physically in seven tables

37. Data Storage and Access
Data storage and access involve strategic business tools
Strategic tools for data storage and access
Data warehouse – dimensions
Data mart
Data Mining

38. Data Storage and Access
Logical and Physical Storage
Logical storage
Characters
Data element or data item
Logical record
Physical storage
Physical record or block
Buffer
Blocking factor

39. Data Storage and Access
Data Coding and Storage
Binary digits
Bit
Byte
EBCDIC, ASCII, and Binary
Unicode

40. Data Storage and Access
Data Coding and Storage
Storing dates
Y2K Issue
Most date formats now are based on the model established by the International Organization for Standardization (ISO)
Absolute date

41. Data Control User ID Password Permissions Encryption Backup
Recovery procedures
Audit log files
Audit fields

42. Chapter Summary
Files and tables contain data about people, places, things, or events that affect the information system
DBMS designs are more powerful and flexible than traditional file-oriented systems

43. Chapter Summary
An entity-relationship (ERD) is a graphic representation of all system entities and the relationships among them
A code is a set of letters or numbers used to represent data in a system
The most common database models are relational and object-oriented

44. Chapter Summary
Logical storage is information seen through a user’s eyes, regardless of how or where that information actually is organized or stored
Physical storage is hardware-related and involves reading and writing blocks of binary data to physical media
File and database control measures include limiting access to the data, data encryption, backup/recovery procedures, audit-trail files, and internal audit fields

45. Chapter Summary
Chapter 9 complete