1. Chapter 7

2. Chapter Objectives Explain data design concepts and data structures
Describe file processing systems and various types of files
Understand database systems and define the components of a database management system (DBMS)
Describe Web-based data design 3

3. Chapter Objectives
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
Explain the importance of codes and describe various coding schemes 3

4. Chapter Objectives
Describe relational and object-oriented database models
Explain data warehousing and data mining
Differentiate between logical and physical storage and records
Explain data control measures

5. 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 control 4

6. Data Design Concepts Data Structures
A file or table contains data about people, places, things, or events that interact with the system
File-oriented system
File processing system
Database system

7. Data Design Concepts Overview of File Processing Potential problems
Data redundancy
Data integrity
Rigid data structure

8. Data Design Concepts Overview of File Processing
Uses various types of files
Master file
Table file
Transaction file
Work file – scratch file
Security file
History file

9. Data Design Concepts Overview of Database Systems
A properly design database system offers a solution to the problems of file processing
Provides an overall framework that avoids data redundancy and supports a real-time, dynamic environment
Database management system (DBMS)
The main advantage of a DBMS is that it offers timely, interactive, and flexible data access

10. Data Design Concepts Overview of Database Systems Advantages
Scalability
Better support for client/server systems
Economy of scale
Flexible data sharing
Enterprise-wide application – database administrator (DBA)
Stronger standards

11. Data Design Concepts Overview of Database Systems Advantages
Controlled redundancy
Better security
Increased programmer productivity
Data independence

12. Data Design Concepts Database Tradeoffs
Because DBMSs are powerful, they require more expensive hardware, software, and data networks capable of supporting a multi-user environment
More complex than a file processing system
Procedures for security, backup, and recovery are more complicated and critical

13. 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

14. 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

15. 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

16. 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

17. Web-Based Database Design
Characteristics of Web-Based Design
In a Web-based design, the Internet serves as the front end, or interface, for the database management system
Internet technology provides enormous power and flexibility
Web-based systems are popular because they offer ease of access, cost-effectiveness, and worldwide connectivity

18. Web-Based Database Design
Internet Terminology
Web browser
Web page
HTML – Hypertext Markup Language
Tags
Web server
Web site
Intranet

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

20. Web-Based Database Design
Connecting a Database to the Web
Database must be connected to the Internet or intranet
Middleware
Macromedia’s ColdFusion

21. Web-Based Database Design
Data Security
Web-based data must be totally secure, yet easily accessible to authorized users
To achieve this goal, 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

22. Data Design Terminology
Definitions
Entity
Table or file
Field
Attribute
Common field
Record
Tuple

23. Data Design Terminology
Key Fields
Primary key
Combination key
Composite key
Concatenated key
Multi-valued key
Candidate key
Nonkey field
Foreign key
Secondary key

24. Data Design Terminology
Referential Integrity
Validity checks can help avoid data input errors

25. Entity-Relationship Diagrams
An entity is a person, place, thing, or event for which data is collected and maintained
Provides an overall view of the system, and a blueprint for creating the physical data structures
Entity-relationship diagram

26. 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

27. Entity-Relationship Diagrams
Types of Relationships
One-to-one relationship (1:1)
One-to-many relationship (1:M)
Many-to-many relationship (M:N)
Associative entity
Cardinality
Cardinality notation
Crow’s foot notation
Unified Modeling Language (UML)

28. Normalization Table design
Involves four stages: unnormalized design, first normal form, second normal form, and third normal form
Most business-related databases must be designed in third normal form

29. 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)

30. Normalization Repeating Groups and Unnormalized Designs
Often occur in manual documents prepared by users
Unnormalized design

31. Normalization First Normal Form Second 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
Second Normal Form
To understand second normal form (2NF), you must understand the concept of functional dependence
Functionally dependent

32. Normalization Second Normal Form
A standard process exists for converting a table from 1NF to 2NF
Create and name a separate table for each field in the existing primary key
Create a new table for each possible combination of the original primary key fields
Study the three tables and place each field with its appropriate primary key

33. Normalization Second Normal Form
Four kinds of problems are found with 1NF designs that do not exist in 2NF
Consider the work necessary to change a particular product’s description
1NF tables can contain inconsistent data
Adding a new product is a problem
Deleting a product is a problem

34. 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

35. Normalization A Normalization Example
To show the normalization process, consider the familiar situation, which depicts several entities in a school advising system: ADVISOR, COURSE, and STUDENT

36. 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 transmission time, and decrease data entry time
Can reduce data input errors

37. Using Codes During Data Design
Types of Codes
Sequence codes
Block sequence codes
Alphabetic codes
Category codes
Abbreviation codes – mnemonic codes
Significant digit codes
Derivation codes
Cipher codes
Action codes

38. Using Codes During Data Design
Developing a Code
Keep codes concise
Allow for expansion
Keep codes stable
Make codes unique
Use sortable codes
Avoid confusing codes
Make codes meaningful
Use a code for a single purpose
Keep codes consistent

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

40. 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

41. Database Models Object-Oriented Databases
Many systems developers are using object-oriented database (OODB) design as a natural extension of the object-oriented analysis process
Object Data standard
Object Database Management Group (ODMG)
Each object has a unique object identifier

42. Data Storage and Access
Data storage and access involve strategic business tools
Strategic tools for data storage and access
Data warehouse - dimensions

43. Data Storage and Access
Strategic tools for data storage and access
Data Mining
Increase average pages viewed per session
Increase number of referred customers
Reduce clicks to close
Increase checkouts per visit
Increase average profit per checkout

44. 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

45. Data Storage and Access
Data Storage Formats
Binary digits
Bit
Byte
EBCDIC and ASCII
Unicode

46. Data Storage and Access
Data Storage Formats
Binary
Binary storage format
Integer format
Long integer format
Other binary formats exist for efficient storage of exceedingly long numbers

47. Data Storage and Access
Selecting a Data Storage Format
In many cases, a user can select a specific data storage format
For example, when using Microsoft Office, you can store documents, spreadsheets, and databases in Unicode-compatible form by using the font called Arial Unicode MS
Best answer is it depends on the situation

48. Data Storage and Access
Date Fields
Most date formats now are based on the model established by the International Organization for Standardization (ISO)
Can be sorted easily and used in comparisons
Absolute date
Best method depends on how the specific date will be printed, displayed, or used in a calculation

49. Data Control
File and database control must include all measures necessary to ensure that data storage is correct, complete, and secure
A well-designed DBMS must provide built-in control and security features, including subschemas, passwords, encryption, audit trail files, and backup and recovery procedures to maintain data

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

51. 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 49

52. Chapter Summary
Data design tasks include creating an initial ERD; assigning data elements to an entity; normalizing all table designs; and completing the data dictionary entries for files, records, and data elements
Logical storage is information seen through a user’s eyes, regardless of how or where that information actually is organized or stored 49

53. Chapter Summary
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
Chapter 7 complete 49