Chapter 5


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Chapter 5

  1. 1. Principles of Information Systems Eighth Edition Chapter 5 Organizing Data and Information
  2. 2. Why Learn About Database Systems? <ul><li>Database systems process and organize large amounts of data </li></ul><ul><li>Examples: </li></ul><ul><ul><li>Marketing manager can access customer data </li></ul></ul><ul><ul><li>Corporate lawyer can access past cases and opinions </li></ul></ul>
  3. 3. Introduction <ul><li>Database: an organized collection of data </li></ul><ul><li>Database management system (DBMS): group of programs to manage database </li></ul><ul><ul><li>Manipulates database </li></ul></ul><ul><ul><li>Provides an interface between database and the user of the database and other application programs </li></ul></ul><ul><li>Database administrator (DBA): skilled IS professional who directs all activities related to an organization’s database </li></ul>
  4. 4. Data Management <ul><li>Without data and the ability to process it, an organization could not successfully complete most business activities </li></ul><ul><li>Data consists of raw facts </li></ul><ul><li>To transform data into useful information, it must first be organized in a meaningful way </li></ul>
  5. 5. The Hierarchy of Data <ul><li>Bit (a binary digit): represents a circuit that is either on or off </li></ul><ul><li>Byte: typically made up of eight bits </li></ul><ul><li>Character: a byte represents a character; the basic building block of information </li></ul><ul><ul><li>Can be an uppercase letter, lowercase letter, numeric digit, or special symbol </li></ul></ul><ul><li>Field: typically a name, number, or combination of characters that describes an aspect of a business object or activity </li></ul>
  6. 6. The Hierarchy of Data (continued) <ul><li>Record: collection of related data fields </li></ul><ul><li>Table: collection of related records </li></ul><ul><li>File: collection of related tables/ records </li></ul><ul><li>Database: collection of integrated and related files </li></ul><ul><li>Hierarchy of data </li></ul><ul><ul><li>Bits, characters, fields, records, files, and databases </li></ul></ul>
  7. 7. The Hierarchy of Data (continued) Figure 5.1: The Hierarchy of Data Table
  8. 8. Data Entities, Attributes, and Keys <ul><li>Entity: generalized class of people, places, or things (objects) for which data is collected, stored, and maintained </li></ul><ul><li>Attribute: characteristic of an entity </li></ul><ul><li>Data item: specific value of an attribute </li></ul><ul><li>Key: field or set of fields in a record that is used to identify the record </li></ul><ul><li>Primary key: field or set of fields that uniquely identifies the record </li></ul>
  9. 9. Data Entities, Attributes, and Keys (continued) Figure 5.2: Keys and Attributes
  10. 10. The Database Approach <ul><li>Traditional approach to data management: separate data files are created and stored for each application program </li></ul><ul><li>Database approach to data management: a pool of related data is shared by multiple application programs </li></ul><ul><ul><li>Offers significant advantages over the traditional file-based approach </li></ul></ul>
  11. 11. The Database Approach (continued) Figure 5.3: The Database Approach to Data Management
  12. 12. The Database Approach (continued) Table 5.1: Advantages of the Database Approach
  13. 13. The Database Approach (continued) Table 5.1: Advantages of the Database Approach (continued)
  14. 14. The Database Approach (continued) Table 5.2: Disadvantages of the Database Approach
  15. 15. Data Modeling and the Relational Database Model <ul><li>When building a database, an organization must consider: </li></ul><ul><ul><li>Content: What data should be collected and at what cost? </li></ul></ul><ul><ul><li>Access: What data should be provided to which users and when? </li></ul></ul><ul><ul><li>Logical structure: How should data be arranged so that it makes sense to a given user? </li></ul></ul><ul><ul><li>Physical organization: Where should data be physically located? </li></ul></ul>
  16. 16. Data Modeling <ul><li>Building a database requires two types of designs </li></ul><ul><ul><li>Logical design: abstract model of how the data should be structured and arranged to meet an organization’s information needs </li></ul></ul><ul><ul><li>Physical design: starts from the logical database design and fine-tunes it for performance and cost considerations </li></ul></ul>
  17. 17. Data Modeling (continued) <ul><li>Data model: diagram of data entities and their relationships </li></ul><ul><li>Entity-relationship (ER) diagrams: data models that use basic graphical symbols to show the organization of and relationships between data </li></ul>
  18. 18. Data Modeling (continued) Figure 5.4: An Entity-Relationship (ER) Diagram for a Customer Order Database
  19. 19. The Relational Database Model <ul><li>Relational model: describes data in which all data elements are placed in two-dimensional tables, called relations, that are the logical equivalent of files </li></ul><ul><ul><li>Each row of a table represents a data entity </li></ul></ul><ul><ul><li>Columns of the table represent attributes </li></ul></ul><ul><ul><li>Domain: allowable values for data attributes </li></ul></ul>
  20. 20. The Relational Database Model (continued) Figure 5.5: A Relational Database Model
  21. 21. The Relational Database Model (continued) <ul><li>Selecting: eliminates rows according to certain criteria </li></ul><ul><li>Projecting: eliminates columns in a table </li></ul><ul><li>Joining: combines two or more tables </li></ul><ul><li>Linking: manipulating two or more tables that share at least one common data attribute to provide useful information and reports </li></ul>
  22. 22. The Relational Database Model (continued) Figure 5.6: A Simplified ER Diagram Showing the Relationship Between the Manager, Department, and Project Tables
  23. 23. The Relational Database Model (continued) Figure 5.7: Linking Data Tables to Answer an Inquiry
  24. 24. The Relational Database Model (continued) <ul><li>Data cleanup: process of looking for and fixing inconsistencies to ensure that data is accurate and complete </li></ul><ul><ul><li>Eliminate redundancies and anomalies </li></ul></ul>
  25. 25. Database Management Systems (DBMSs) <ul><li>Creating and implementing the right database system ensures that the database will support both business activities and goals </li></ul><ul><li>DBMS: a group of programs used as an interface between a database and application programs or a database and the user </li></ul>
  26. 26. Overview of Database Types <ul><li>Flat file </li></ul><ul><ul><li>Simple database program whose records have no relationship to one another </li></ul></ul><ul><li>Single user </li></ul><ul><ul><li>Only one person can use the database at a time </li></ul></ul><ul><ul><li>Examples: Access, FileMaker, and InfoPath </li></ul></ul><ul><li>Multiple user </li></ul><ul><ul><li>Allows dozens or hundreds of people to access the same database system at the same time </li></ul></ul><ul><ul><li>Examples: Oracle, Sybase, and IBM </li></ul></ul>
  27. 27. Providing a User View <ul><li>Schema: description of the entire database </li></ul><ul><ul><li>Typically used by large database systems to define tables and other database features associated with a person or user </li></ul></ul><ul><li>A DBMS can reference a schema to find where to access the requested data in relation to another piece of data </li></ul>
  28. 28. Creating and Modifying the Database <ul><li>Data definition language (DDL): collection of instructions and commands used to define and describe data and relationships in a specific database </li></ul><ul><ul><li>Allows the database’s creator to describe the data and relationships that are to be contained in the schema </li></ul></ul><ul><li>Data dictionary: detailed description of all the data used in the database </li></ul>
  29. 29. Creating and Modifying the Database (continued) Figure 5.10: Using a Data Definition Language to Define a Schema
  30. 30. Creating and Modifying the Database (continued) Figure 5.11: A Typical Data Dictionary Entry
  31. 31. Storing and Retrieving Data <ul><li>When an application program requests data from the DBMS, the application program follows a logical access path </li></ul><ul><li>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 </li></ul>
  32. 32. Storing and Retrieving Data (continued) Figure 5.12: Logical and Physical Access Paths
  33. 33. Manipulating Data and Generating Reports <ul><li>Data manipulation language (DML): commands that manipulate the data in a database </li></ul><ul><li>Structured Query Language (SQL) </li></ul><ul><ul><li>Adopted by the American National Standards Institute (ANSI) as the standard query language for relational databases </li></ul></ul><ul><li>Once a database has been set up and loaded with data, it can produce reports, documents, and other outputs </li></ul>
  34. 34. Database Administration <ul><li>Role of the database administrator (DBA): plan, design, create, operate, secure, monitor, and maintain databases </li></ul><ul><li>DBA works with both users and programmers </li></ul><ul><li>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 </li></ul>
  35. 35. Popular Database Management Systems <ul><li>Popular DBMSs for end users include Microsoft’s Access and FileMaker Pro </li></ul><ul><li>Complete database management software market includes: </li></ul><ul><ul><li>Software for professional programmers </li></ul></ul><ul><ul><li>Databases for midrange, mainframe, and supercomputers </li></ul></ul><ul><li>Examples of open-source database systems: PostgreSQL and MySQL </li></ul><ul><li>Many traditional database programs are now available on open-source operating systems </li></ul>
  36. 36. Special-Purpose Database Systems <ul><li>Some specialized database packages are used for specific purposes or in specific industries </li></ul><ul><ul><li>Israeli Holocaust Database ( ) </li></ul></ul><ul><ul><li>Hazmat database </li></ul></ul><ul><ul><li>Art and Antique Organizer Deluxe </li></ul></ul><ul><li>Special-purpose database by Tableau can be used to store and process visual images </li></ul>
  37. 37. Selecting a Database Management System <ul><li>Important characteristics of databases to consider </li></ul><ul><ul><li>Database size </li></ul></ul><ul><ul><li>Database cost </li></ul></ul><ul><ul><li>Concurrent users </li></ul></ul><ul><ul><li>Performance </li></ul></ul><ul><ul><li>Integration </li></ul></ul><ul><ul><li>Vendor </li></ul></ul>
  38. 38. Using Databases with Other Software <ul><li>DBMSs can act as front-end or back-end applications </li></ul><ul><ul><li>Front-end applications interact directly with people or users </li></ul></ul><ul><ul><li>Back-end applications interact with other programs or applications </li></ul></ul>
  39. 39. Database Applications <ul><li>Today’s database applications manipulate the content of a database to produce useful information </li></ul><ul><li>Common manipulations are searching, filtering, synthesizing, and assimilating the data contained in a database using a number of database applications </li></ul>
  40. 40. Linking Databases to the Internet <ul><li>Linking databases to the Internet is important for many organizations and people </li></ul><ul><li>Semantic Web </li></ul><ul><ul><li>Developing a seamless integration of traditional databases with the Internet </li></ul></ul><ul><ul><li>Allows people to access and manipulate a number of traditional databases at the same time through the Internet </li></ul></ul>
  41. 41. Data Warehouses, Data Marts, and Data Mining <ul><li>Data warehouse: database that collects business information from many sources in the enterprise, covering all aspects of the company’s processes, products, and customers </li></ul><ul><li>Data mart: subset of a data warehouse </li></ul><ul><li>Data mining: information-analysis tool that involves the automated discovery of patterns and relationships in a data warehouse </li></ul>
  42. 42. Data Warehouses, Data Marts, and Data Mining (continued) Figure 5.17: Elements of a Data Warehouse
  43. 43. Data Warehouses, Data Marts, and Data Mining (continued) Table 5.8: Common Data-Mining Applications
  44. 44. Business Intelligence <ul><li>Business intelligence (BI): 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 </li></ul><ul><ul><li>Turns data into useful information that is then distributed throughout an enterprise </li></ul></ul>
  45. 45. Business Intelligence (continued) <ul><li>Competitive intelligence: aspect of business intelligence limited to information about competitors and the ways that knowledge affects strategy, tactics, and operations </li></ul><ul><li>Counterintelligence: steps an organization takes to protect information sought by “hostile” intelligence gatherers </li></ul>
  46. 46. Distributed Databases <ul><li>Distributed database </li></ul><ul><ul><li>Database in which the data may be spread across several smaller databases connected via telecommunications devices </li></ul></ul><ul><ul><li>Gives corporations more flexibility in how databases are organized and used </li></ul></ul><ul><li>Replicated database </li></ul><ul><ul><li>Database that holds a duplicate set of frequently used data </li></ul></ul>
  47. 47. Online Analytical Processing (OLAP) <ul><li>Software that allows users to explore data from a number of different perspectives </li></ul>
  48. 48. Online Analytical Processing (OLAP) (continued) Table 5.9: Comparison of OLAP and Data Mining
  49. 49. Object-Oriented and Object-Relational Database Management Systems <ul><li>Object-oriented database: database that stores both data and its processing instructions </li></ul><ul><ul><li>Method: procedure or action </li></ul></ul><ul><ul><li>Message: request to execute or run a method </li></ul></ul>
  50. 50. Object-Oriented and Object-Relational Database Management Systems (continued) <ul><li>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 </li></ul><ul><li>Object-relational database management system (ORDBMS): DBMS capable of manipulating audio, video, and graphical data </li></ul>
  51. 51. Visual, Audio, and Other Database Systems <ul><li>Databases for storing images </li></ul><ul><li>Databases for storing sound </li></ul><ul><li>Virtual database systems: allow different databases to work together as a unified database system </li></ul><ul><li>Other special-purpose database systems </li></ul><ul><ul><li>Spatial data technology: stores and accesses data according to the locations it describes and permits spatial queries and analysis </li></ul></ul>