Transcript ch08
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Chapter 8
Data and Knowledge
Management
Management Information Systems, Second Edition
Effy Oz
Learning Objectives
When you finish this chapter, you will
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Know the difference between traditional file
organization methods and the database approach.
Know how database management systems are used
to construct databases, populate them with data,
and manipulate the data to produce information.
Be familiar with the different database models and
the advantages and disadvantages of each model.
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Learning Objectives
Know the most important features and operations of
a relational database.
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Understand how databases are changing business
operations across industries and what impact they
might have on our personal lives.
Understand the concepts of data warehousing and
data-mining and their use in business.
Recognize the need for knowledge storage and
management and be able to give examples of the
ways knowledge is managed in organizations.
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Managing Digital Data
The Traditional File Approach
Disadvantages
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Program/Data Dependency
Data Redundancy
Data Integrity
Moving to Databases
Database Management System (DBMS)
Queries: Request data from specified fields
Security: Giving users different views addresses
security issue
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Managing Digital Data
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Figure 8.1 The layout of a personnel file in traditional file
organization.
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Managing Digital Data
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Figure 8.2 Different information making up a student record
retained in three different sites.
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Managing Digital Data
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Figure 8.3 Data hierarchy
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Managing Digital Data
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Figure 8.4 Different database views reveal different
combinations of data
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Managing Digital Data
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Figure 8.5 Different views of one employee
database
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Managing Digital Data
Traditional Files vs. Databases:
Pros and Cons
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Traditional File Advantages
Simplicity
Efficiency
Customization
Database Advantages
Reduced data redundancy
Application/data independence
Better control
Flexibility
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Database Models
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Figure 8.6 Advantages and disadvantages of database models
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Database Models
The Hierarchical Model
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Records are related hierarchically -- each
category is a subcategory of the next level up
Disadvantages of hierarchical databases
To retrieve a record, a user must start at the root
and navigate the hierarchy.
If a link is broken, the entire branch is lost.
Requires considerable data redundancy because
child records can have only one parent
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Database Models
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Figure 8.7 A schematic diagram of a hierarchical
database (a) and a sample part of a hierarchical database
showing relationships among different records (b)
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Database Models
The Network Model
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Allows a record to be linked to more than
one parent
Supports many-to-many (N:M)
relationships
Advantage of the network model
Reduced data redundancy
Disadvantages of the network model
Complicated to build and difficult to maintain
Difficult to navigate
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Database Models
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Figure 8.8 A schematic diagram of a network database (a)
and a sample of part of a network database showing
relationships among different records (b)
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Database Models
The Relational Model
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Consists of tables; links among entities are
maintained with foreign keys
Advantages of relational databases
Same advantages of a network database without
the complications.
Easier to conceptualize and maintain.
Virtually all DBMSs offered for
microcomputers accommodate the relational
model.
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Database Models
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Figure 8.9 A schematic diagram of a relational database (a)
and a sample part of a relational database showing different
tables (b)
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Database Models
Keys
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Fields whose values identify records for
display or processing.
Primary key
Uniquely identifies a record
Linking
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Database Models
The Object-Oriented Structure
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Affords maintenance of data along with the
applications that process them
Entity-Relationship Diagrams
Conceptual blueprint of a database
Graphical representation of all entity
relationships
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Database Models
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Figure 8.10 An entity-relationship diagram
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Components of Database
Management Systems
The Schema
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Describes the structure of the database
The Data Dictionary (Metadata)
Maintains all information supplied by the
developer when constructing the schema
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Components of Database
Management Systems
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Figure 8.12 A typical data dictionary for a staff file
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Components of Database
Management Systems
Data Definition Language (DDL)
Used to construct the schema
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Figure 8.13 Data definition language to create a
schema in NOMAD
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Components of Database
Management Systems
Data Manipulation Language (DML)
Used to query the database
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Figure 8.14 A Paradox query by example
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Relational Operations
Data Manipulation
Select, Project, Join
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Structured Query Language (SQL)
International standard DDL and DML for
relational DBMS.
Advantages of using SQL
Users do not need to learn different DDLs and DMLs.
SQL can be embedded in widely used 3rd generation
languages, increasing efficiency and effectiveness.
Programmer not forced to rewrite statements since SQL
statements are portable.
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Relational Operations
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Figure 8.15 A join table of professors and their
students
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Popular Database
Management Systems
DATABASE MODEL
Hierarchical
Network
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Relational
Object-Relational
PRODUCT
Focus
IMS
Ramis
ADABAS
Image
Access
DB2
dBASE V
EDA/SQL
FoxPro
Ingres
NOMAD
Oracle
Paradox
Rbase
SQL/DS
SQL Server
Sybase
ObjectStore
Universal
Server
Illustra
VENDOR
Information Builders International
IBM
Online Software International
Software AG of North America
Hewlett-Packard
Microsoft
IBM
Borland International
Information Builders International
Microsoft
Ask Group
Must Software International
Oracle
Borland International
Microrim
IBM
Microsoft
Sybase
Object Design
Informix
HARDWARE
Mainframe/PC
Mainframe
Mainframe
Mainframe
Mainframe
PC
Mainframe
PC
PC
PC
PC
Mainframe/PC
Mainframe/PC
PC
PC
Mainframe
PC
PC
PC
PC
Informix
PC
Figure 8.16 Popular DBMSs
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Database Architecture
Distributed Databases
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Replication
Full copy of the entire database is stored at all
sites
Fragmentation
Parts of database are stored where they are
most often accessed
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Database Architecture
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Figure 8.17 A replicated database: each computer holds a
copy of the entire database
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Database Architecture
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Figure 8.18 A fragmented database: each computer
holds only the part of the database that is most
frequently accessed by the local users
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Database Architecture
Shared Resource and Client/Server
Systems
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Four basic client/server models
Applications run at a server
Applications run on local PCs
Applications run on both the local PCs and the
server
Applications and key elements of the database
are split between the PCs and the server
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Database Architecture
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Figure 8.19 Shared resource and client/server
architectures
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Web Databases
Databases on the Web
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Catalogs
Libraries
Directories
Client lists and profiles
When linking a database to the
Internet, consider
Which application to use
How to ensure Web surfers do not interfere
with database updates
How to maintain security
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Data Warehousing
Data warehouse
Collection of data that supports
management decision making
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Phases in Building a Data Warehouse
Extraction Phase
Cleansing Phase
Loading Phase
Data Mining
Selecting, exploring, and modeling data to
discover unknown relationships
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Data Warehousing
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Figure 8.20 Data are warehoused for analysis and reporting
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Data-Mining
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Figure 8.21 Potential applications of data-mining
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Knowledge Management
The attempt by organizations to:
Transfer knowledge into databases
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Filter and separate the most relevant
knowledge
Organize knowledge in databases that either
Allow other employees to easily access the
knowledge
“Push” specific knowledge to employees based on
their prespecified needs
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Ethical and Societal Issues
A Too-Risky Info Highway
Out of Hand -- Out of Control
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DBMSs allow organizations to collect,
maintain, and sell vast amounts of private
personal data easily.
Where is the Information Going?
Many consumers provide information
daily without being aware of where it is
actually going.
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Ethical and Societal Issues
A Too-Risky Info Highway
Personal Data Matched, Sliced , and Diced
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Pieces of personal data may be matched and put
together to reveal private life in unexpected ways.
Error Propagation
In case of errors, it may be impossible to trace your
data to all organizations that have it.
The Upside
Database technology enables better and faster
services.
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