1. Systems Analysis and Design 8th Edition
Chapter 9
Data Design

2. Introduction
You will develop a physical plan for data organization, storage, and retrieval
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

3. 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
or File processing system
Database system

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

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

6. 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

7. Data Design Concepts
The Evolution from File Systems to Database Systems
Some Advantages
Scalability
Economy of scale
Enterprise-wide application – database administrator (DBA)
Controlled redundancy
Data independence

8. 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

9. 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

10. 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

11. 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

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

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

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

15. 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

16. Data Design Terminology
Definitions
Entity
Table or file
Field
Record

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

18. 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

19. Entity-Relationship Diagrams
Drawing an ERD (Pg. 402)
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

20. 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)

21. Entity-Relationship Diagrams
Cardinality (Pg. 405)
Cardinality notation
Crow’s foot notation
Unified Modeling Language (UML)
Now that you understand database elements and their relationships, you can start designing tables

22. 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)

23. Normalization Repeating Groups and Unnormalized Design (Pg. 407)
Often occur in manual documents prepared by users
Unnormalized
Enclose the repeating group of fields within a second set of parentheses

24. 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

25. Normalization Second Normal Form (Pg. 410)
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 fully 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

26. Normalization Third Normal Form (Ppg. 411 - 412)
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 (transitional dependency)
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

27. Normalization
A Normalization Example
Standard notation formats?

28. Normalization Solve for Third Normal Form Use standard notation format
Stud Stud Campus Major Course Course Instr Instr Instr Grade
ID Name Address ID Title ID Name Location

29. Normalization Solve for Third Normal Form
Stud Stud. Campus Major Course Course Instr Instr Instr Grade
ID Name Address ID Title ID Name Location
STUDENT (STUDENT_ID, STUDENT_NAME, CAMPUS_ADDRESS, MAJOR, INSTR_ID)
COURSE (COURSE_ID, COURSE_TITLE, INSTR_ID)
INSTRUCTOR (INSTR_ID, INSTR_NAME, INSTR_LOCATION)
GRADES (STUDENT_ID, COURSE_ID, GRADE)

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 (379)
Block sequence codes (MSIT3050)
Alphabetic codes (MA)
Significant digit codes (01610)
Derivation codes (magazine subscriber code)
Cipher codes (letters represent numbers)
Action codes (“D” to Display)

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. Steps in Database Design
Create the initial ERD
Assign all data elements to entities
Create 3NF designs for all tables
Verify all data dictionary entries
After creating your final ERD and normalized table designs, you can transform them into a database

35. Database Models Relational Databases
The relational model was introduced during the 1970s and became popular because it was flexible and powerful
Because all the tables are linked, a user can request data that meets specific conditions
New entities and attributes can be added at any time without restructuring the entire database

36. Database Models Object-Oriented Databases
Many systems developers are using object-oriented database (OODB) design
Object Management Group (OMG)
Each object has a unique object identifier

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