Managing Data Resources

1
Managing Data Resources
Chapter 7
2
Outlines

• Challenges to access information using
  traditional file management technologies.
• Database management systems.
• Managerial and organizational requirements for
  implementing a database environment successfully.

3
Organizing Data in a Traditional File Environment
File Organization Terms and Concepts

• Bit Smallest unit of data binary digit (0,1)
• Byte Group of bits that represents a single
  character
• Field Group of words or complete number
• Record Group of related fields
• File Group of records of the same type

4
Organizing Data in a Traditional File Environment
File Organization Terms and Concepts

• Database Group of related files
• Entity Person, place, thing, or event about
  which information must be kept
• Attribute A piece of information describing a
  particular entity
• Key field Field that uniquely identifies every
  record in a file

5
Organizing Data in a Traditional File Environment
The data hierarchy
Figure 7-1
6
Organizing Data in a Traditional File Environment
Entities and attributes
Figure 7-2
7
Organizing Data in a Traditional File Environment
Traditional file processing
Figure 7-3
8
Organizing Data in a Traditional File Environment
Problems with the Traditional File Environment

• Data redundancy
• Program-data dependence
• Lack of flexibility
• Poor security
• Lack of data-sharing and availability

9
Organizing Data in a Traditional File Environment
Problems with the Traditional File Environment

• Data redundancy The presence of duplicate data
  in multiple data files so that the same data are
  stored in more than one place or location.
• Waste storage resources
• Data inconsistency the same attribute having
  different values (loose user confidence).

10
Organizing Data in a Traditional File Environment
Problems with the Traditional File Environment

• Program-data dependence Program changes lead to
  data changes.
• 2-digit versus 4-digit year
• Sequence in a record
• Delimited character

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Organizing Data in a Traditional File Environment
Problems with the Traditional File Environment

• Lack of flexibility
• Data merge
• Ad hoc reports
• Poor security
• Theft of data can occur in any department without
  the knowledge of managers
• Lack of data-sharing and availability

12
The Database Approach to Data Management
Database Management Systems

• Database
• Collection of centralized data
• Controls redundant data
• Data stored so as to appear to users in one
  location
• Services multiple application

13
The Database Approach to Data Management
The contemporary database environment
Figure 7-4
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The Database Approach to Data Management
Database Management Systems

• Database Management System (DBMS)
• Creates and maintains databases
• Eliminates requirement for data definition
  statements
• Acts as interface between application programs
  and physical data files
• Separates logical and physical views of data

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The Database Approach to Data Management
Database Management Systems

• Three Components to a DBMS
• Data definition language Formal language
  programmers use to specify structure of database
• Data manipulation language For extracting data
  from database, e.g. SQL
• Data dictionary Tool for storing, organizing
  definitions of data elements and data
  characteristics

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The Database Approach to Data Management
Sample data dictionary report
Figure 7-5
17
The Database Approach to Data Management
Database Management Systems

• How a DBMS Solves Problems of a
• Traditional File Environment
• Reduces data redundancy
• Eliminates data inconsistency
• Uncouples programs from data
• Increases access and availability of data
• Allows central management of data, data use, and
  security

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The Database Approach to Data Management
Types of Databases

• Relational DBMS
• Represents data as two-dimensional tables called
  relations
• Relates data across tables based on common data
  element (the power of RDBMS)
• Examples DB2, Oracle, MS SQL Server

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The Database Approach to Data Management
The relational data model
Figure 7-6
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The Database Approach to Data Management
Types of Databases

• Three Basic Operations in a Relational Database
• Select Creates subset of rows that meet specific
  criteria
• Join Combines relational tables to provide users
  with information
• Project Enables users to create new tables
  containing only relevant information

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The Database Approach to Data Management
The three basic operations of a relational DBMS
Figure 7-7
22
The Database Approach to Data Management
Types of Databases

• Hierarchical DBMS
• Older system presenting data in tree-like
  structure
• Models one-to-many parent-child relationships
• Found in large legacy systems requiring intensive
  high-volume transactions Banks insurance
  companies
• Examples IBMs IMS

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The Database Approach to Data Management
A hierarchical database for a human resources
system
Figure 7-8
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The Database Approach to Data Management
Types of Databases

• Network DBMS
• Older logical database model
• Models many-to-many parent-child relationships
• Example Student course relationship Each
  student has many courses each course has many
  students

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The Database Approach to Data Management
The network data model
Figure 7-9
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The Database Approach to Data Management
Types of Databases

• Disadvantages of Hierarchical and
• Network DBMS
• Outdated
• Less flexible compared to RDBMS
• Lack support for ad-hoc and English language-like
  queries

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The Database Approach to Data Management
Types of Databases

• Object-Oriented Databases (OODBMS)
• Stores data and procedures as objects
• Better able to handle graphics and recursive data
• Data models more flexible
• Slower than RDBMS
• Hybrid object-relational DBMS

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Creating a Database Environment
Designing Databases

• Two Design Phases in Creating Database
• Conceptual (logical) design Abstract model of
  database from business perspective
• Physical design How the database is actually
  arranged on direct access storage devices

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Creating a Database Environment
Designing Databases

• Conceptual Database Design
• Identifies relationships between data elements
• Identifies most efficient way to group data
  elements
• Identifies redundant data elements
• Identifies grouping of data elements needed for
  specific applications

30
Creating a Database Environment
Designing Databases

• Entity-Relationship Diagram
• A methodology for documenting databases that
  illustrates the relationship between various
  elements in the database
• Normalization
• The process of creating small, stable, and
  adaptive data structures from complex groups of
  data when designing a relational database

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Creating a Database Environment
An entity-relationship diagram
Figure 7-10
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Creating a Database Environment
An unnormalized relation for ORDER
Figure 7-11
33
Creating a Database Environment
A normalized relation for ORDER
Figure 7-12
34
Creating a Database Environment
Distributing Databases

• Distributed Database
• Pros
• Partitioned or replicated to more than one
  location
• Increases service and responsiveness
• Reduces vulnerability of single, massive central
  site
• Cons
• Depend on telecommunication lines
• Pose security risks through distribution of
  sensitive data
• Central data must be updated or justified with
  local data

35
Creating a Database Environment
Distributed databases
Figure 7-13
36
Creating a Database Environment
Key organizational elements in the database
environment
Figure 7-14
37
Creating a Database Environment
Management Requirements for Database Systems

• Data Administration
• Develop information policy
• Define information requirements
• Plan for data
• Oversee logical database design and database
  dictionary development
• Monitor use of information

38
Creating a Database Environment
Management Requirements for Database Systems

• Data Planning and Modeling Methodology
• Enterprise-wide planning for data
• Enterprise Analysis Identify key entities,
  attributes, and relationships that constitute the
  organizations data

39
Creating a Database Environment
Management Requirements for Database Systems

• Database Technology, Management,
• and Users
• Databases require DBMS software and staff
• Database design group defines and organizes
  structure and content of database
• Database administration establish physical
  database, logical relations, access rules
• Permit non-professional access to database
  through SQL
• Devote more resources to end-user training

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Database Trends
Multidimensional Data Analysis

• Online Analytical Processing (OLAP)
• Multidimensional data analysis
• Enables users to view the same data in different
  ways using multiple dimensions
• Each aspect of information product, price,
  region represents a different dimension

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Database Trends
Multidimensional data model
Figure 7-15
42
Database Trends
Data Warehouses and Datamining

• Data warehouse Stores current and historical
  data for reporting, analysis
• Data mart Subset of data warehouse with summary
  of data for specific users
• Datamining Techniques to find hidden patterns,
  relationships in large pools of data to infer
  rules for predicting future trends

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Database Trends
Components of a data warehouse
Figure 7-16
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Database Trends
Data Warehouses and Datamining

• Benefits of Data Warehouses
• Improved information and accessibility
• Ability to model and remodel data
• Enable access to data without affecting
  performance of underlying operational legacy
  systems

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Database Trends
Window on Management

• Data Reveal New Sales Opportunities
• How did the use of data warehouses and datamining
  help management at these companies make better
  decisions?
• What value do these systems provide?

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Database Trends
Data Warehouses and Datamining

• Hypermedia database
• Organizes data as network of nodes
• Links nodes in pattern specified by user
• Supports text, graphic, sound, video and
  executable programs

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Database Trends
A hypermedia database
Figure 7-17
48
Database Trends
Databases and the Web

• Linking Internal Databases to the Web
• Database server
• Hosts DBMS
• Receives SQL requests
• Provides required data
• Middleware
• Works between Web server and DBMS to take
  requests
• Handles connectivity to database
• Can be application server or CGI scripts

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Database Trends
Linking internal databases to the Web
Figure 7-18
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Database Trends
Databases and the Web

• Advantages to Web Access to Databases
• Browser software easy to use little training
• Web interface requires no changes to internal
  database
• Costs less than custom interfaces

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Database Trends
Window on Technology

• Web Access for Royal Bank Statements
• Pays Off
• What are the business benefits of providing a Web
  interface for the Bankbook Reconstruct
  application?
• What value does this application provide the
  company and its customers?