Management information system ralp 7e ch05

Principles of Information Systems, Seventh Edition 2• The database approach to data management provides significant advantages over the traditional file-based approach • Define general

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Principles of Information Systems, Seventh Edition 2

• The database approach to data management provides significant

advantages over the traditional file-based approach

• Define general data management concepts and terms,

highlighting the advantages and disadvantages of the

database approach to data management

• Describe the relational database model and outline its basic

features

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• A well-designed and well-managed database is an extremely

valuable tool in supporting decision making

• Identify the common functions performed by all database

management systems and identify popular end-user database

management systems

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• The number and types of database applications will continue to

evolve and yield real business benefits

• Identify and briefly discuss current database applications

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Introduction

• Database management system (DBMS): group of programs that

manipulate database and provide interface between database and

users

• Database administrator (DBA): a skilled information systems

professional who directs all activities related to organization’s

database

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Data Management: The Hierarchy of Data

• A bit (a binary digit) represents a circuit that is either on or off

• A byte is typically 8 bits

• Character: each byte represents a character, the basic building

block of information

• Field: typically a name, number, or combination of characters that

describes an aspect of a business object or activity

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The Hierarchy of Data (continued)

• Record: a collection of related data fields

• File: a collection of related records

• Database: a collection of integrated and related files

• Hierarchy of data: formed by bits, characters, fields, records, files,

and databases

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Principles of Information Systems, Seventh Edition 8Figure 5.1: The Hierarchy of Data

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Data Entities, Attributes, and Keys

• Entity: a generalized class of people, places, or things (objects) for

which data is collected, stored, and maintained

• Attribute: a characteristic of an entity

• Data item: the specific value of an attribute

• Key: a field or set of fields in a record that is used to identify the

record

• Primary key: a field or set of fields that uniquely identifies the

record

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Principles of Information Systems, Seventh Edition 10Figure 5.2: Keys and Attributes

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The Traditional Approach Versus the

Database Approach

• Traditional approach: separate data files are created and stored for

each application program

• Results in data redundancy: duplication of data in separate

files

• Data redundancy conflicts with data integrity (the degree to

which the data in any one file is accurate)

• Database approach: approach whereby a pool of related data is

shared by multiple application programs; offers significant

advantages over traditional file-based approach

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Principles of Information Systems, Seventh Edition 12Figure 5.3: The Traditional Approach to

Data Management

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Principles of Information Systems, Seventh Edition 13Figure 5.4: The Database Approach to

Data Management

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Table 5.1: Advantages of the

Database Approach

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Principles of Information Systems, Seventh Edition 15Table 5.1: Advantages of the Database

Approach (continued)

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Principles of Information Systems, Seventh Edition 16Table 5.2: Disadvantages of the

Database Approach

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Data Modeling and the Relational

Database Model

• When building a database, an organization must consider:

• Content: What data should be collected and at what cost?

• Access: What data should be provided to which users and

when?

• Logical structure: How should data be arranged so that it

makes sense to a given user?

• Physical organization: Where should data be physically

located?

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Data Modeling

• Building a database requires two types of designs:

• Logical design: shows an abstract model of how the data

should be structured and arranged to meet an organization’s information needs

• Physical design: starts from the logical database design

and fine-tunes it for performance and cost considerations

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Data Modeling (continued)

• Data model: a diagram of data entities and their relationships

• Entity-relationship (ER) diagrams: data models that use basic

graphical symbols to show the organization of and relationships

between data

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Principles of Information Systems, Seventh Edition 20Figure 5.5: An Entity-Relationship (ER) Diagram for a Customer Order Database

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The Relational Database Model

• Relational model: describes data in which all data elements are

placed in two-dimensional tables, called relations, that are the

logical equivalent of files

• In the relational model:

• Each row of a table represents a data entity

• Columns of the table represent attributes

• Domain: the allowable values for data attributes

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Principles of Information Systems, Seventh Edition 22Figure 5.6: A Relational Database Model

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Manipulating Data

• Selecting: eliminates rows according to certain criteria

• Projecting: eliminates columns in a table

• Joining: combines two or more tables

• Linking: combines two or more tables using common data attributes

to form a new table with only the unique data attributes

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Database Management Systems

(DBMS)

• A group of programs used as an interface between a database and

application programs or a database and user

• Database types

• Flat file

• Single user

• Multiple users

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Providing a User View

• Schema: a description of the entire database

• User view: the portion of the database a user can access

• Subschemas are used to create different user views

• Subschema: a file that contains a description of a subset of the

database and identifies which users can view and modify the data items in the subset

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Principles of Information Systems, Seventh Edition 26Figure 5.10: The Use of Schemas

and Subschemas

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Creating and Modifying the Database

• Data definition language (DDL)

• A collection of instructions and commands used to define

and describe data and data relationships in a specific

database

• Allows the database’s creator to describe the data and the

data relationships that are to be contained in the schema and subschemas

• Data dictionary: a detailed description of all the data used in the

database

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Principles of Information Systems, Seventh Edition 28Figure 5.11: Using a Data Definition

Language to Define a Schema

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Figure 5.12: A Typical Data

Dictionary Entry

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Storing and Retrieving Data

• When an application program request data from DBMS, the

application program follows a logical access path

• When the DBMS goes to a storage device to retrieve the requested

data, it follows a path to the physical location (physical access path) where the data is stored

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Principles of Information Systems, Seventh Edition 31Figure 5.13: Logical and Physical Access

Paths

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Manipulating Data and Generating Reports

• Data manipulation language (DML): the commands that are used

to manipulate the data in a database

• Structured Query Language (SQL): adopted by the American

National Standards Institute (ANSI) as the standard query language for relational databases

• Once a database has been set up and loaded with data, it can produce

reports, documents, and other outputs

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Principles of Information Systems, Seventh Edition 33Table 5.6: Examples of SQL Commands

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Popular Database Management

Systems

• Popular DBMSs for end users include Microsoft’s Access and

Corel’s Paradox

• The complete database management software market includes

databases by IBM, Oracle, and Microsoft

• Examples of open-source database systems: PostgreSQL and

MySQL

• Many traditional database programs are now available on

open-source operating systems

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Selecting a Database Management

System

• Important characteristics of databases to consider:

• Size of the database

• Number of concurrent users

• Performance

• The ability of the DBMS to be integrated with other

systems

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Selecting a Database Management

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Database Applications: Linking the

Company Database to the Internet

• Corporate databases can be accessed by customers, suppliers, and

company employees through:

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Data Warehouses, Data Marts, and

Data Mining

• Data warehouse: a database that collects business information from

many sources in the enterprise, covering all aspects of the

company’s processes, products, and customers

• Data mart: a subset of a data warehouse

• Data mining: an information-analysis tool that involves the

automated discovery of patterns and relationships in a data

warehouse

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Figure 5.17: Elements of a

Data Warehouse

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Principles of Information Systems, Seventh Edition 40Table 5.8: Common Data-Mining

Applications

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Business Intelligence

• Business intelligence (BI): the process of gathering enough of the

right information in a timely manner and usable form and analyzing

it to have a positive impact on business strategy, tactics, or

operations

• Knowledge management: the process of capturing a company’s

collective expertise wherever it resides and distributing it wherever

it can help produce the biggest payoff

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Distributed Databases

• Distributed database

• A database in which the data may be spread across several

smaller databases connected via telecommunications

devices

• Corporations get more flexibility in how databases are

organized and used

• Replicated database: a database that holds a duplicate set of

frequently used data

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Online Analytical Processing (OLAP)

of different perspectives

Table 5.9: Comparison of OLAP and Data Mining

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Open Database Connectivity (ODBC)

• Standards that ensure that software can be used with any

ODBC-compliant database

• Can be used to export, import, or link tables between different

applications

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Principles of Information Systems, Seventh Edition 45Figure 5.19: Advantages of ODBC

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Object-Oriented and Object-Relational

• Object-oriented database

• Stores both data and its processing instructions

• Method: a procedure or action

• Message: a request to execute or run a method

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Object-Oriented and Object-Relational

(continued)

• Object-oriented database management system (OODBMS):

group of programs that manipulate an object-oriented database and provide a user interface and connections to other application

programs

• Object-relational database management system (ORDBMS):

DBMS capable of manipulating audio, video, and graphical data

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Summary

• Hierarchy of data: bits, characters, fields, records, files, and

databases

• Entity: a generalized class of things (objects) for which data is

collected, stored, and maintained

• Attribute: characteristic of an entity

• Data model: diagram of entities and relationships

• Relational model: describes data in which all elements are placed

in two-dimensional tables called relations

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Summary (continued)

• Selecting: eliminates rows according to certain criteria

• Projecting: eliminates columns in a table

• Database management system (DBMS): group of programs used

as an interface

• Between a database and application programs

• Database and the user

• Data dictionary: detailed description of all the data used in the

database

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Summary (continued)

• Data warehouse: database that collects business information from

all aspects of a company’s processes, products, and customers

• Data mining: an information-analysis tool for the automated

discovery of patterns and relationships in a data warehouse

• Open database connectivity (ODBC) standards: ensure that

software can be used with any ODBC-compliant database

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