File

s, D

ata

base

s, &

E-C

om

merc

e

1

Using Information Technology

Chapter 8

Files, Databases, & E-Commerce

File

s, D

ata

base

s, &

E-C

om

merc

e

2

Files, Databases, & E-CommerceDigital Engines for the New Economy

8.1Managing Files: Basic Concepts

8.2Database Management Systems

8.3Database Models

8.4Features of a Database Management System

8.5Databases & the New Economy: E-Commerce, Data Mining, & B2B Systems

8.6The Ethics of Using Databases: Concerns about Accuracy & Privacy

File

s, D

ata

base

s, &

E-C

om

merc

e

3

8.1 Managing Files: Basic Concepts

• Data storage hierarchy - levels of data stored in a computer:

• Database• Files• Records• Fields• Characters (bytes)• Bits

File

s, D

ata

base

s, &

E-C

om

merc

e

4

Types of Files

•Filename - name given to a file

•Extension - three letters following a period in a filename

•Program files - files containing software instructions

•Data files - files that contain data (words, numbers, pictures, sounds, etc.)

File

s, D

ata

base

s, &

E-C

om

merc

e

5

Types of Files

•ASCII files

•Image (graphic) files

•Audio files

•Animation/video files

•Web files

File

s, D

ata

base

s, &

E-C

om

merc

e

6

Two Types of Data Files

• Master file - • a data file containing

relatively permanent records that are generally updated periodically

• Transaction file - • a temporary holding

file that holds all changes to be made to the master file: additions, deletions, revisions

File

s, D

ata

base

s, &

E-C

om

merc

e

7

Data Access Methods

• Sequential storage -• data is stored and

retrieved in sequence

• Direct access storage -

• the computer can go directly to the information you want

File

s, D

ata

base

s, &

E-C

om

merc

e

8

Offline versus Online Storage

• Offline storage - • data is not directly

accessible for processing until the tape or disk it’s on has been loaded onto an input device

• Online storage -• stored data is

randomly (directly) accessible for processing

File

s, D

ata

base

s, &

E-C

om

merc

e

9

8.2 Database Management Systems

•Database management system (DBMS) - programs that control the structure of a database and access to the data

•Advantages of DBMSes:

• File sharing• Reduced data redundancy• Improved data integrity• Increased security

File

s, D

ata

base

s, &

E-C

om

merc

e

10

Four Types of Database Access

•Individual database - collection of integrated files used by one person

•Shared database - database shared by users in one company or organization in one location

•Distributed database - stored on different computers in different locations and connected by a client/server network

•Public databank - compilation of data that is available to the public

File

s, D

ata

base

s, &

E-C

om

merc

e

11

8.3 Database Models

• Hierarchical database - fields or records are arranged in related groups, resembling a family tree, with child (lower-level) records subordinate to parent (higher-level) records

File

s, D

ata

base

s, &

E-C

om

merc

e

12

Database Models

• Network database - similar to a hierarchical database, but each child record can have more than one parent record

File

s, D

ata

base

s, &

E-C

om

merc

e

13

Database Models

• Relational database - a database which relates (connects) data in different files through the use of a key field, or common data element

File

s, D

ata

base

s, &

E-C

om

merc

e

14

Database Models

•Object-oriented database - database which uses “objects”--software written in small, reusable chunks--as elements within database files

•An object consists of:

• Data in any form, and•

• Instructions on the actions to take on the data

File

s, D

ata

base

s, &

E-C

om

merc

e

15

8.4 Features of a Database Management System

•Data dictionary - a procedures document or disk file that stores the data definitions or a description of the structure of data used in the database

•DBMS utilities - programs that allow you to maintain the database

•Report generator - program for producing an onscreen or printed document from all or part of a database

File

s, D

ata

base

s, &

E-C

om

merc

e

16

Features of a Database Management System

•Access security - a feature allowing DBAs to specify different access privileges for different users

File

s, D

ata

base

s, &

E-C

om

merc

e

17

Features of a Database Management System

•System recovery - features that allow a DBA to recover contents of the database in the event of a hardware or software failure

•Four approaches to system recovery:

• Mirroring• Reprocessing• Rollforward• Rollback

File

s, D

ata

base

s, &

E-C

om

merc

e

18

8.5 Databases & the New Economy: E-Commerce, Data

Mining, & B2B Systems• E-commerce (electronic commerce) - the buying and selling

of products and services through computer networks

File

s, D

ata

base

s, &

E-C

om

merc

e

19

Data Mining

•Data mining (DM) - the computer-assisted process of sifting through and analyzing vast amounts of data in order to extract meaning and discover new knowledge

File

s, D

ata

base

s, &

E-C

om

merc

e

20

Data Mining

1 Data sources:

Point-of-sale transactions in flat files on mainframes; Databases of all kinds; Other--news articles, online articles, etc.; and Data from data warehouses.

2 Data fusion and cleansing3 Data and meta-data4 Data warehouse

File

s, D

ata

base

s, &

E-C

om

merc

e

21

Data Mining

1 Data sources

2 Data fusion and cleansing - putting together the data from various sources and then “scrubbing” the data to eliminate errors and inconsistencies

3 Data and meta-data4 Data warehouse

File

s, D

ata

base

s, &

E-C

om

merc

e

22

Data Mining

1 Data sources

2 Data fusion and cleansing

3 Data and meta-data - cleaned-up data and meta-data (data about data)

4 Data warehouse

File

s, D

ata

base

s, &

E-C

om

merc

e

23

Data Mining

1 Data sources

2 Data fusion and cleansing

3 Data and meta-data

4 Data warehouse - a special database of cleaned up data and meta-data

File

s, D

ata

base

s, &

E-C

om

merc

e

24

Data Mining

•Three kinds of software, or “siftware” tools used to perform data mining finding and analyzing tasks:

• Query-and-reporting tools

• Multidimensional-analysis tools

• Intelligent agents

File

s, D

ata

base

s, &

E-C

om

merc

e

25

Business-to-Business (B2B) Systems

• B2B - a system in which a business sells to other businesses, using the Internet or a private network to cut transaction costs and increase efficiencies

File

s, D

ata

base

s, &

E-C

om

merc

e

26

8.6 Ethics of Using Databases: Concerns about Accuracy &

Privacy• Morphing - process in which a film or video is

displayed on a computer screen and altered pixel by pixel, or dot by dot, into something else

File

s, D

ata

base

s, &

E-C

om

merc

e

27

The Ethics of Using Databases

• Manipulation of video & television

Manipulation of photos

File

s, D

ata

base

s, &

E-C

om

merc

e

28

The Ethics of Using Databases

• Privacy - the right of people not to reveal information about themselves

File

s, D

ata

base

s, &

E-C

om

merc

e

29

The Ethics of Using Databases

• Manipulation of sound

• Monopolizing information