dsi 05 database

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Principles of Information Systems

Eighth Edition

Organizing Data and

Information



Principles of Information Systems, Eighth Edition 2

Learning Objectives

– Define general data management concepts and

terms, highlighting the advantages of the database

approach to data management

– Describe the relational database model and outlineits basic features

– Identify the common functions performed by all

database management systems and identify popular

user database management systems

– Identify and briefly discuss current database

applications




Why Learn About Database Systems?

• Database systems process and organize large

amounts of data

• Examples:

– Marketing manager can access customer data

– Corporate lawyer can access past cases and

opinions




Introduction

• Database: an organized collection of data

• Database management system (DBMS): group of

programs to manage database

– Manipulates database

– Provides an interface between database and the

user of the database and other application programs

• Database administrator (DBA): skilled IS

professional who directs all activities related to anorganization’s database




Data Management

• Without data and the ability to process it, an

organization could not successfully complete most

business activities

• Data consists of raw facts• To transform data into useful information, it must

first be organized in a meaningful way




The Hierarchy of Data

• Bit (a binary digit): represents a circuit that is

either on or off

• Byte: typically made up of eight bits

• Character: a byte represents a character; thebasic building block of information

– Can be an uppercase letter, lowercase letter,

numeric digit, or special symbol

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

characters that describes an aspect of a business

object or activity




The Hierarchy of Data (continued)

• Record: collection of related data fields

• File: collection of related records

• Database: collection of integrated and related files

• Hierarchy of data

– Bits, characters, fields, records, files, and databases




The Hierarchy of Data (continued)

Figure 5.1: The Hierarchy of Data




Data Entities, Attributes, and Keys

• Entity: generalized class of people, places, or

things (objects) for which data is collected, stored,

and maintained

• Attribute: characteristic of an entity• Data item: specific value of an attribute

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

identify the record

• Primary key: field or set of fields that uniquely

identifies the record




Data Entities, Attributes, and Keys

(continued)

Figure 5.2: Keys and Attributes




The Database Approach

• Traditional approach to data management:

separate data files are created and stored for each

application program

• Database approach to data management: a pool

of related data is shared by multiple application

programs

– Offers significant advantages over the traditional file-

based approach




The Database Approach (continued)

Figure 5.3: The Database Approach to Data Management





Table 5.1: Advantages of the Database Approach





Table 5.1: Advantages of the Database Approach (continued)





Table 5.2: Disadvantages of the Database Approach




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?




Data Modeling

• Building a database requires two types of designs

– Logical design: 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




Data Modeling (continued)

• Data model: diagram of data entities and their

relationships

• Entity-relationship (ER) diagrams: data models

that use basic graphical symbols to show theorganization of and relationships between data




Data Modeling (continued)

Figure 5.4: An Entity-Relationship (ER) Diagram for a Customer Order

Database




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 – Each row of a table represents a data entity

– Columns of the table represent attributes

– Domain: allowable values for data attributes





(continued)

Figure 5.5: A Relational Database Model





(continued)

• Selecting: eliminates rows according to certain

criteria

• Projecting: eliminates columns in a table

• Joining: combines two or more tables• Linking: manipulating two or more tables that

share at least one common data attribute to

provide useful information and reports





(continued)

Figure 5.6: A Simplified ER Diagram Showing the Relationship Between

the Manager, Department, and Project Tables





(continued)

Figure 5.7: Linking Data Tables to Answer an Inquiry





(continued)

• Data cleanup: process of looking for and fixinginconsistencies to ensure that data is accurate andcomplete

– Eliminate redundancies and anomalies





(continued)

Table 5.3: Fitness Center Dues





(continued)

Table 5.5: Dues Paid

Table 5.4: Fitness Center Members




Database Management Systems

(DBMSs)

• Creating and implementing the right database

system ensures that the database will support both

business activities and goals

• DBMS: a group of programs used as an interface

between a database and application programs or a

database and the user




Overview of Database Types

• Flat file

– Simple database program whose records have no

relationship to one another

• Single user – Only one person can use the database at a time

– Examples: Access, FileMaker, and InfoPath

• Multiple user

– Allows dozens or hundreds of people to access the

same database system at the same time

– Examples: Oracle, Sybase, and IBM




Providing a User View

• Schema: description of the entire database

– Typically used by large database systems to define

tables and other database features associated with a

person or user • A DBMS can reference a schema to find where to

access the requested data in relation to another

piece of data




Creating and Modifying the Database

• Data definition language (DDL): collection of

instructions and commands used to define and

describe data and relationships in a specific

database – Allows the database’s creator to describe the data

and relationships that are to be contained in the

schema

• Data dictionary: detailed description of all the dataused in the database





(continued)

Figure 5.10: Using a Data Definition Language to Define a Schema





(continued)

Figure 5.11: A Typical Data Dictionary Entry




Storing and Retrieving Data

• When an application program requests data from

the DBMS, the application program follows a

logical access path

• When the DBMS goes to a storage device toretrieve the requested data, it follows a path to the

physical location (physical access path) where the

data is stored

• Concurrency control?




Storing and Retrieving Data

(continued)

Figure 5.12: Logical and Physical Access Paths




Manipulating Data and Generating

Reports

• Data manipulation language (DML): commands

that manipulate the data in a database

• Structured Query Language (SQL)

– Adopted by the American National StandardsInstitute (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




Manipulating Data and Generating

Reports (continued)

Table 5.6: Examples of SQL Commands




Database Administration

• Role of the database administrator (DBA): plan,

design, create, operate, secure, monitor, and

maintain databases

• DBA works with both users and programmers• A data administrator is responsible for defining and

implementing consistent principles for a variety of

data issues, including setting data standards and

data definitions; a nontechnical position




Popular Database Management

Systems

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

• Complete database management software marketincludes:

– Software for professional programmers

– Databases for midrange, mainframe, andsupercomputers

• Examples of open-source database systems:

PostgreSQL and MySQL• Many traditional database programs are now

available on open-source operating systems




Special-Purpose Database Systems

• Some specialized database packages are used for

specific purposes or in specific industries

– Israeli Holocaust Database (www.yadvashem.org )

– Hazmat database – Art and Antique Organizer Deluxe

• Special-purpose database by Tableau can be used

to store and process visual images




Selecting a Database Management

System

• Important characteristics of databases to consider

– Database size

– Database cost

– Concurrent users – Performance

– Integration

– Vendor




Using Databases with Other Software

• DBMSs can act as front-end or back-end

applications

– Front-end applications interact directly with people or

users – Back-end applications interact with other programs

or applications




Database Applications

• Today’s database applications manipulate the

content of a database to produce useful information

• Common manipulations are searching, filtering,

synthesizing, and assimilating the data contained ina database using a number of database

applications




Linking Databases to the Internet

• Linking databases to the Internet is important for

many organizations and people

• Semantic Web

– Developing a seamless integration of traditionaldatabases with the Internet

– Allows people to access and manipulate a number of

traditional databases at the same time through the

Internet




Data Warehouses, Data Marts, and

Data Mining

• Data warehouse: database that collects business

information from many sources in the enterprise,

covering all aspects of the company’s processes,

products, and customers• Data mart: subset of a data warehouse

• Data mining: information-analysis tool that

involves the automated discovery of patterns and

relationships in a data warehouse





Data Mining (continued)

Figure 5.17: Elements of a Data Warehouse





Data Mining (continued)

Table 5.8: Common Data-Mining Applications




Distributed Databases

• Distributed database

– Database in which the data may be spread across

several smaller databases connected via

telecommunications devices

– Gives corporations more flexibility in how databases

are organized and used

• Replicated database

– Database that holds a duplicate set of frequentlyused data




Object-Oriented and Object-Relational


• Object-oriented database: database that stores

both data and its processing instructions

– Method: procedure or action

– Message: request to execute or run a method

Object Oriented and Object Relational




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




Visual, Audio, and Other Database

Systems

• Databases for storing images

• Databases for storing sound

• Virtual database systems: allow different

databases to work together as a unified databasesystem

• Other special-purpose database systems

– Spatial data technology: stores and accesses data

according to the locations it describes and permitsspatial queries and analysis




Summary

• Database: a collection of integrated and related files

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

files, and databases

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

• Database approach to data management: a pool of

related data is shared by multiple application

programs• Data model: diagram of entities and relationships




Summary (continued)

• Relational model: describes data in which all

elements are placed in two-dimensional tables

called relations

• Database management system (DBMS): group of programs used as an interface between a database

and application programs or a database and the

user

• Role of the database administrator (DBA): plan,design, create, operate, secure, monitor, and

maintain databases



Summary (continued)

• Data warehouse: database that collects business

information from all aspects of a company’s

processes, products, and customers

• Data mining: information-analysis tool for theautomated discovery of patterns and relationships

in a data warehouse

• Object-oriented database: database that stores

both data and its processing instructions

dsi 05 database

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