A.I.S. Class 5: Outline I Learning Objectives for Chapter 2 I - - PowerPoint PPT Presentation

September 20, 2000

• Dr. Peter R Gillett

1

A.I.S. Class 5: Outline

I Learning Objectives for Chapter 2 I Elements of Information Systems I Discussion Questions and Problems I Automated Procedures for Sales and

Collections

September 20, 2000

• Dr. Peter R Gillett

2

Learning Objectives for Chapter 2

I After studying this chapter you should

be able to:

N distinguish between data and information N explain the hierarchy of data N describe alternative field formats, record keys, and

coding systems

N explain various types of files N discuss the steps in the data processing cycle N discuss data input options N explain the various file organization, file access, and

file update options

N discuss the relative merits and drawbacks of batch

versus on-line processing

N describe and discuss the systems approach

September 20, 2000

• Dr. Peter R Gillett

3

Data versus Information

I Data represents raw facts I Information is data made meaningful I Meaningful data is:

F relevant - able to affect the user’s decision F reliable F timely F accurate, free from errors F complete

September 20, 2000

• Dr. Peter R Gillett

4

Hierarchy of Data

I Bit (BInary digiT) I Byte (usually 8 bits) I Field (multiple bytes making a unit of data

• e.g., a name, a value)

I Record (group of related fields - e.g., an

individual customer)

I File (group of records - e.g., all customers) I Database (multiple logically related files)

September 20, 2000

• Dr. Peter R Gillett

5

Data Representation

I EBCDIC v ASCII I Field Sizes I Field Formats

F Numeric F Text (alphanumeric) F Date/Time F Currency F Boolean F Counters F BLOBS

September 20, 2000

• Dr. Peter R Gillett

6

Record Keys

I Primary key I Candidate keys I Secondary key I Composite keys (concatenated keys) I Foreign keys (will appear in Chapter 6) I Non-key attributes

September 20, 2000

• Dr. Peter R Gillett

7

Coding Systems

I Sequence code - each item sequentially

numbered

I Block code- ranges of numbers

reserved for each category of items

I Group code - each digit or group of

digits signifies a different aspect

I Mnemonic code - letters suggestive of

the item being coded

September 20, 2000

• Dr. Peter R Gillett

8

File Types

I Master files - permanent information I Transaction files - used to update I Reference files - used for lookup I Table files - same as reference I History files - old archives I Backup files - duplicates for security

F Grandfather - father - son

I Suspense files – temporary storage pending

resolution

September 20, 2000

• Dr. Peter R Gillett

9

The Data Processing Cycle

N Data input

² batch ² on-line

N Data preparation

² validation ² sorting

N Data processing

² batch ² real-time

N File maintenance N Information output

September 20, 2000

• Dr. Peter R Gillett

10

File Access

I Sequential files I Random (or direct) access files I Hashing algorithms I Clashes I Overflow areas I Indexed files (ISAM)

September 20, 2000

• Dr. Peter R Gillett

11

File Maintenance

I Batch processing

F efficiency F control

I On-line processing I Real-time processing

F master file up-to-date F no data preparation required F faster access

I Report-time processing

September 20, 2000

• Dr. Peter R Gillett

12

The General Systems Model

I A system is a set of elements which operate

together to achieve some objective

F Recall our definition of organizations!

I Systems have

N inputs N processes N outputs N boundaries N environments

September 20, 2000

• Dr. Peter R Gillett

13

Factoring Systems

I Factoring - subsystems I Interfaces I Independence I Decoupling (e.g. inventory) I Buffers I Control systems

N sensor N standard N comparison N activation

September 20, 2000

• Dr. Peter R Gillett

14

Reminder

I Learning Objectives I Discussion Questions: Group responsibility I Key Terms

F be sure you can explain what each of these is

September 20, 2000

• Dr. Peter R Gillett

15

Discussion Questions and Problems

I Working in your groups, review the Discussion

Questions for Chapter 2 and identify any that the group collectively cannot answer

I Develop agreed group solutions for Problems 3,

4, 5 & 7

I Discuss the narrative and flowcharts in the

Chapter 1 Appendix for automated sales and collections cycles

I Groups will be asked to present their solutions in

class