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Managing Data Resources

Chapter 7. Managing Data Resources. Objectives. Why do businesses have trouble finding the information they need in their information systems? How does a database management system help businesses improve the organization of their information?. Objectives.

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Managing Data Resources

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  1. Chapter 7 Managing Data Resources

  2. Objectives • Why do businesses have trouble finding the information they need in their information systems? • How does a database management system help businesses improve the organization of their information?

  3. Objectives • How do the principal types of database models affect the way businesses can access and use information? • What are the managerial and organizational requirements of a database environment? • What new tools and technologies can make databases more accessible and useful?

  4. Management Challenges • Organizational obstacles to a database environment • Cost/benefit considerations

  5. 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

  6. 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

  7. Organizing Data in a Traditional File Environment The data hierarchy Figure 7-1

  8. Organizing Data in a Traditional File Environment Entities and attributes Figure 7-2

  9. 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

  10. Organizing Data in a Traditional File Environment Traditional file processing Figure 7-3

  11. 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

  12. The Database Approach to Data Management The contemporary database environment Figure 7-4

  13. 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

  14. 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

  15. The Database Approach to Data Management Sample data dictionary report Figure 7-5

  16. 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

  17. 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 • Examples: DB2, Oracle, MS SQL Server

  18. The Database Approach to Data Management The relational data model Figure 7-6

  19. 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

  20. The Database Approach to Data Management The three basic operations of a relational DBMS Figure 7-7

  21. 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

  22. The Database Approach to Data Management A hierarchical database for a human resources system Figure 7-8

  23. 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

  24. The Database Approach to Data Management The network data model Figure 7-9

  25. 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

  26. 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

  27. Creating a Database Environment Designing Databases Two Design Exercises 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

  28. 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

  29. 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

  30. Creating a Database Environment An entity-relationship diagram Figure 7-10

  31. Creating a Database Environment An unnormalized relation for ORDER Figure 7-11

  32. Creating a Database Environment A normalized relation for ORDER Figure 7-12

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

  34. Creating a Database Environment Distributed databases Figure 7-13

  35. Creating a Database Environment Key organizational elements in the database environment Figure 7-14

  36. 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

  37. Creating a Database Environment Management Requirements for Database Systems Data Planning and Modeling Methodology • Enterprise-wide planning for data • Identify key entities, attributes, and relationships that constitute the organization’s data

  38. 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

  39. 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

  40. Database Trends Multidimensional data model Figure 7-15

  41. 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

  42. Database Trends Components of a data warehouse Figure 7-16

  43. 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

  44. 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?

  45. 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

  46. Database Trends A hypermedia database Figure 7-17

  47. 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

  48. Database Trends Linking internal databases to the Web Figure 7-18

  49. 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

  50. 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?

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