Dfd

1. E. Wainright Martin  Carol V. Brown  Daniel W. DeHayes
Jeffrey A. Hoffer  William C. Perkins
MANAGING
INFORMATION
TECHNOLOGY
FIFTH EDITION
CHAPTER 5
THE DATA RESOURCE

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 Organizations could not function long
without critical business data
 Cost to replace data would be very high
 Time to reconcile inconsistent data may
be too long
 Data often needs to be accessed quickly
WHY MANAGE DATA?
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 Data should be:
 Cataloged
 Named in standard ways
 Protected
 Accessible to those with a need to know
 Maintained with high quality
WHY MANAGE DATA?
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TECHNICAL ASPECTS OF
MANAGING THE DATA RESOURCE
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Data model –
overall map for business data needed to effectively
manage the data
The Data Model

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 Data modeling involves:
 Methodology, or steps followed to identify
and describe data entities
 Notation, or a way to illustrate data entities
graphically
The Data Model
TECHNICAL ASPECTS OF
MANAGING THE DATA RESOURCE

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 Entity-relationship diagram (ERD)
 Most common method for representing a
data model and organizational data needs
 Captures entities and their relationships
 Entities – things about which data are
collected
 Attributes – actual elements of data that are
to be collected
TECHNICAL ASPECTS OF
MANAGING THE DATA RESOURCE
The Data Model

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Figure 5.1 Entity-Relationship Diagram
NOTE:
• Entities are Customer, Order, and Product.
• Attributes of the Customer entity could be
customer last name, first name, street, city, …
TECHNICAL ASPECTS OF
MANAGING THE DATA RESOURCE
The Data Model

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 Enterprise modeling
 Top-down approach
 Describes organization and data
requirements at high level, independent of
reports, screens, or detailed specifications
 Not biased by how business operates today
TECHNICAL ASPECTS OF
MANAGING THE DATA RESOURCE
Data Modeling

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Enterprise Modeling Steps:
 Divide work into major
functions
 Divide each function into
processes
 Divide processes into
activities
 List data entities
assigned to each activity
 Identify relationships
between entities
TECHNICAL ASPECTS OF
MANAGING THE DATA RESOURCE
Data Modeling
Figure 5.2 Enterprise Decomposition
for Data Modeling

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 View integration
 Bottom-up approach
 Each report, screen, form, document
produced from databases first … each
called a user view
TECHNICAL ASPECTS OF
MANAGING THE DATA RESOURCE
Data Modeling

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View Integration Steps:
 Create user views
 Identify data elements in each user view and put into a
structure called a normal form
 Normalize user views
 Integrate set of entities from normalization into one
description
TECHNICAL ASPECTS OF
MANAGING THE DATA RESOURCE
Data Modeling
Normalization –
process of creating simple data structures from more complex
ones

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 Data modeling guidelines:
 Objective – effort must be justified by need
 Scope – broader scope, more chance of
failure
 Outcome – uncertainty leads to failure
 Timing – consider an evolutionary approach
TECHNICAL ASPECTS OF
MANAGING THE DATA RESOURCE
Data Modeling

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TECHNICAL ASPECTS OF
MANAGING THE DATA RESOURCE
Database Architecture
Database –
shared collection of logically related data, organized to
meet needs of an organization
Database Architecture –
way in which the data are structured and stored in the
database

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Figure 5.3 The Data Pyramid

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TECHNICAL ASPECTS OF
MANAGING THE DATA RESOURCE
 Six basic database architectures:
1. Hierarchical (top-down organization)
2. Network (high-volume transaction processing)
3. Relational (data arranged in simple tables)
4. Object-oriented (data and methods encapsulated in object
classes)
5. Object-relational (hybrid of relational and object-
oriented)
6. Multidimensional (used by data warehouses)
Database Architecture

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TECHNICAL ASPECTS OF
MANAGING THE DATA RESOURCE
Tools for Managing Data
Database Management System (DBMS) –
support software used to create, manage, and protect
organizational data

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TECHNICAL ASPECTS OF
MANAGING THE DATA RESOURCE
 A DBMS helps manage data by providing
seven functions:
1. Data storage, retrieval, update
2. Backup
3. Recovery
4. Integrity control
5. Security control
6. Concurrency control
7. Transaction control
Tools for Managing Data

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TECHNICAL ASPECTS OF
MANAGING THE DATA RESOURCE
 Most popular type of database architecture
is relational
 Not all relational systems are identical.
 Best effort to date for standardizing
relational databases is SQL
Tools for Managing Data

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TECHNICAL ASPECTS OF
MANAGING THE DATA RESOURCE
 Contains:
 Definition of each entity,
relationship, and data
element
 Display formats
 Integrity rules
 Security restrictions
 Volume and sizes
 List of applications that use
the data
Tools for Managing Data
Data Dictionary/Directory (DD/D) –
central encyclopedia of data definitions and usage
information … a database about data

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TECHNICAL ASPECTS OF
MANAGING THE DATA RESOURCE
Database Programming
Query language –
a 4 GL, nonprocedural programming language to obtain
data from a database, often provided by the DBMS
SQL query language example:
SELECT ORDER#, CUSTOMER#, CUSTNAME,
ORDER-DATE FROM CUSTOMER, ORDER
WHERE ORDER-DATE > ’04/12/05’
AND CUSTOMER.CUSTOMER# =
ORDER.CUSTOMER#

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 The need to manage data is permanent
 Data can exist at several levels
 Application software should be separate from the
database
 Application software can be classified by how they
treat data
1. Data capture
2. Data transfer
3. Data analysis and presentation
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MANAGING DATA
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Principles in Managing Data

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Figure 5.4

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 Application software should be
considered disposable
 Data should be captured once
 There should be strict data standards
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MANAGING DATA
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Principles in Managing Data

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MANAGING DATA
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Principles in Managing Data
Figure 5.5 Types of Data Standards

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MANAGING DATA
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The Data Management Process
Figure 5.6 Asset Management Functions

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Figure 5.7 The Data Warehouse

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MANAGERIAL ISSUES IN
MANAGING DATA
 Organizations should have policies regarding:
Data ownership
Data administration
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Data Management Policies

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MANAGING DATA
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Data Ownership
Corporate information policy –
foundation for managing the ownership of data

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Figure 5.8 Example Data Access Policy

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Data Administration
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Key functions of the data administration group:
 Promote and control data sharing
 Analyze the impact of changes to application systems when data
definitions change
 Maintain the data dictionary
 Reduce redundant data and processing
 Reduce system maintenance costs and improve system
development productivity
 Improve quality and security of data
 Insure data integrity
MANAGERIAL ISSUES IN
MANAGING DATA

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Data Administration
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Key functions of the database administrator (DBA):
 Tuning database management systems.
 Selection and evaluation of and training on database technology.
 Physical database design.
 Design of methods to recover from damage to databases.
 Physical placement of databases on specific computers and
storage devices.
 The interface of databases with telecommunications and other
technologies.
MANAGERIAL ISSUES IN
MANAGING DATA