Introduction to Information Technology 2 nd Edition Turban

Introduction to Information Technology 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. Chapter 5: Managing Organizational Data and Information Prepared by: Roberta M. Roth, Ph. D. University of Northern Iowa Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 5 -1

Chapter Preview v In this chapter, we will study: ØBasic data management terminology ØStoring data in traditional files and problems with this approach ØThe database approach to storing data ØHow data is organized to create a data base ØComponents of a DBMS ØHow companies utilize their stored data Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 5 -2

Basics of Data Arrangement and Access v The Data Hierarchy ØRecall… 8 bits => 1 byte => 1 character ØField - a logical grouping of characters into a word, a small group of words, or a complete number ØRecord - a logical grouping of related fields ØFile - a logical grouping of related records ØDatabase - a logical grouping of related files Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 5 -3

Data Management Terminology v Entity - a person, place, thing, or event about which information is maintained Ø Records describe entities v Attribute - each characteristic or quality describing a particular entity Ø Fields describe attributes v Primary Key - field that uniquely identifies the record v Secondary Key - field does not identify the records uniquely, but can be used to form logical groups of records Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 5 -4

Traditional File Environment v The organization has multiple applications with related data files Each application has a specific data file related to it, containing all the data records needed by the application Each application comes with an associated applicationspecific data file Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 5 -5

Problems: Traditional File Environment v Data redundancy – same piece of data found in several places. v Data inconsistency – various copies of data no longer agree. v Data isolation – data in several application data files is hard to access and integrate. v Security – may be difficult to limit access to various data items in applications. v Data integrity – data must be accurate and correct. v Application/data dependence – applications are developed based on the way data is stored. Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 5 -6

Locating Data in Databases v Two choices: Centralized or Distributed v Choice will affect user accessibility, query response time, data entry, security, and cost v Option 1: Centralized database Ø All the related files are in one physical location Ø Provides database administrators with the ability to work on a database as a whole at one location Ø Data consistency is improved and security is easier Ø Files are only accessible via the centralized host computer Ø Recovery from disasters is easier Ø Vulnerable to a single point of failure Ø Speed problem due to transmission delays Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 5 -7

Locating Data in Databases (continued) v Option 2: Distributed database Ø Complete copies of a database, or portions of a database, are in more than one location, close to the user Ø Type 1: Replicated database • Copies of database in many locations • Reduced single-point-of-failure problems • Increased user access responsiveness Ø Type 2: Partitioned databases • A portion of the database in each location • Each location responsible for its own data Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 5 -8

Database Development v First, develop a Conceptual design - an abstract model of the database from the user or business perspective v Second, organize with Entity-Relationship (ER) modeling Øprocess of planning the database design ØEntity classes Instance Identifiers Relationships Course Number Course Name Course Time Course Place 1: M Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. can have Professor ID Number 1: 1 Name Department 5 -9

Entity-relationship model v Types of relationships: Ø One-to-one: a student has one schedule; a schedule belongs to one student Ø One-to-many: a course has one professor; a professor has one or more courses Ø Many-to-many: a student has one or more courses; a course has one or more students Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 5 -10

Database Development v Third, analyze the data structure by applying the Normalization process Ømethod that reduces a relational database to its most streamlined form ØHelps achieve • minimum redundancy • maximum data integrity • best processing performance Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 5 -11

Non-normalized table and its problems * If an order contains many parts, you will have many repeating groups of part information. How will you know how much space to set aside for all the groups of part information? * The customer number, name, address, etc. must be repeated in every order. If the customer moves, how will you make sure that all occurrences of the address get updated correctly in all the order records? Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 5 -12

Database Development v Fourth, physically implement the data structure in the database management system software ØCreate tables ØDefine fields and field properties ØEstablish primary keys ØDefine table relationships ØAdd actual data (records) to tables Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 5 -13

Database Management Systems v A set of software programs that provide access to a database v Data is stored in one location, from which it can be updated and retrieved v Application programs are given access to the stored data by various mechanisms Ø Maintaining the integrity of stored information Ø Managing security and user access Ø Recovering information when the system fails Ø Accessing various database functions from within an application Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 5 -14

DBMS: Logical versus Physical View v Logical view - represents data in a format that is meaningful to a user (e. g. , tables with fields and records) v Physical view - deals with the actual, physical arrangement and location of data in the direct access storage devices (DASD) v DBMSs shield the user from having to know about the physical location of the data; user only has to know the logical way it’s organized Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 5 -15

DBMS Components v Data Model Ø Defines the way data are conceptually structured v Data Definition Language (DDL) Ø Used to define the content and structure of the data base Ø Users define their logical view (schema) of the database using the DDL Ø Physical characteristics of records and fields are defined Ø Relationships, primary keys, and security can be established Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 5 -16

More DBMS Components v Data Manipulation Language (DML) ØUsed to query the contents of the database, store or update information in the database, and develop database applications ØStructured query language (SQL) - most popular relational database language v Data Dictionary Østores definitions of data elements and data characteristics Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 5 -17

DBMS Benefits v Improved strategic use of corporate data v Reduced complexity of IS environment v Reduced data redundancy and inconsistency v Enhanced data integrity v Application/data independence v Improved security v Reduced development and maintenance costs v Improved IS flexibility v Increased data access Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 5 -18

Logical Data Models v A manager’s ability to use a database depends on how the database is structured logically and physically. v In a logically structuring database, consider the characteristics of the data and how the data will be accessed. v Three common data models : hierarchical, network, and relational v Using these models, database designer can build logical or conceptual view of data that can then be physically implemented into virtually any database with any DBMS. Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 5 -19

Logical Data Models (continued) v Relational model is common in PC environment v v because it is simple to understand. Relational model provides high flexibility and ease of use. Relational model provides slower search and access times; a problem in high-volume business settings. Hierarchical data model gives best processing speeds, but poor query flexibility. Network data model gives pretty good processing speeds and pretty good query flexibility, but is very complex. Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 5 -20

Emerging and Specialized Data Models v Multidimensional v Object-oriented data model v Hypermedia v Geographic information system database v Knowledge database v Multimedia database v Small-footprint database Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 5 -21

Using the Stored Data v Access to accurate and timely information is critical in today’s business environment. v Much information is collected by TPS, but access to and insight from that data may be limited. v Many organizations are working to improve information access and availability. Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 5 -22

Using the Stored Data (continued) v Data warehouse: Ø a database system designed to support management decision making. Ø Emphasis is on organizing data in convenient, meaningful ways so that users can get their queries answered. Ø Current and historical, detail and summarized data are included. Ø Metadata (data about data) is included to help keep track of the data warehouse content. v Data mart: small scale, simpler data warehouse. Easier to implement. Targets smaller business segments. Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 5 -23

Using the Stored Data (continued) v Data mining: Ø Extracting new insights from data warehouse Ø Sophisticated tools employ algorithms to discover hidden patterns, correlations, and relationships. • • • Classifying Clustering Associating Sequencing Forecasting Ø What can we learn (examples)? • Market segments and customer characteristics • Customer buying patterns • Fraudulent behavior Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 5 -24

Chapter Summary v Traditional file structures lead to numerous data management problems v DBMS help resolve many of those problems v Users are concerned with the logical view of data. v When organizations have created well structured databases, decision making and insight will improve through data warehouses and the use of data mining tools. Introduction to Information Technology, 2 nd Edition Turban, Rainer & Potter © 2003 John Wiley & Sons, Inc. 5 -25

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