Chapter 1 ® Introduction to Database Management
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Chapter 1 ® Introduction to Database Management Presentation Transcript

  • 1. Chapter 1
    • Introduction to Database Management
    Database Management
  • 2. Objectives
    • Provide a general introduction to the field of database management
    • Introduce basic terminology
    • Describe the advantages and disadvantages of database processing
    • Provide a brief history of database management
    • Describe the hierarchical and network database models
  • 3. Introduction
    • Chapter uses the example of Henry, the owner of four bookstores
    • Current file system is difficult and costly to use
    • Interested in different categories of data, called entities , including books, authors, publishers, and branches, and the relationships between these entities
  • 4. Henry’s Basic Data
    • File - an organized collection of data about a single entity
    • Record - pertains to a specific person, place, thing, or event
    • Fields - contain certain facts about that specific person, place, thing, or event
  • 5. Figure 1.1 Branch File
  • 6. Figure 1.2 Publisher and Author Files
  • 7. Figure 1.3 Book File
  • 8. Figure 1.4 Book-Author and Book-Branch Files
  • 9. Using a Database Management System (DBMS)
    • A DBMS is a program or collection of programs whose function is to manage a database on behalf of the people who use it.
    • Database design is the determination of the structure of the database.
  • 10. Figure 1.5 Branch Form
  • 11. Figure 1.6 Book Form
  • 12. Figure 1.7 Book Report
  • 13. Figure 1.8 Main Switchboard
  • 14. Figure 1.9 Maintain Data Switchboard
  • 15. Entities, Attributes, and Relationships
    • Entity – a person, place, thing, or event
    • Attribute – a property of an entity
      • For the entity “Person,” attributes could include eye color and height
    • Relationship – an association between entities
      • Publishers are related to the books they publish, and a book is related to its publisher
  • 16. Figure 1.10 Entities and Attributes
  • 17. Figure 1.11 One-to-Many Relationship
  • 18. Files and Databases
    • Data file – stores information on a single entity and the attributes of that entity
    • Database – a structure that can store information about multiple types of entities, the attributes of these entities, and the relationships among the entities
  • 19. Database Management System (DBMS)
    • DBMS programs manipulate databases either for the user, or a program the user is executing
    • Mainframe DBMSs have been used since the 1960s
    • Since the mid-1980s, DBMSs on PCs possess many of the features of their mainframe counterparts
  • 20. Figure 1.12 Using Database Management Systems
  • 21. Database Processing
    • Database processing – the data to be processed are stored in a database and the data in the database are being manipulated by the DBMS
    • Nondatabase approach
      • Duplication of data
      • Extremely difficult to fulfill requirements that involve data from more than one system
  • 22. Figure 1.13 Nondatabase Approach
  • 23. Database Processing
    • Database approach
      • Common database managed by a DBMS
      • Each entity appears only once in the system, reducing the duplication of data
      • With all data being in a single database, it is possible to list all information concerning the entities
  • 24. Figure 1.14 Database Approach
  • 25. Figure 1.15 Advantages of Database Processing
  • 26. Advantages of Database Processing
    • Getting more information from the same amount of data
      • When all the data for various systems are stored in a single database, the information becomes available, as well as the process of retrieving the information can be quick and easy
  • 27. Advantages of Database Processing
    • Sharing of data
      • Several users can have access to the same piece of data
    • Balancing conflicting requirements
      • A person or group, often called Database Administration/Administrator (DBA) can structure the database in such a way that it benefits the entire organization, not just a single group
  • 28. Advantages of Database Processing
    • Controlling redundancy
      • Not only saves space, but makes the updating process easier
    • Consistency
      • Consistency is a direct result of redundancy, so by reducing redundancy, there is much less potential for this sort of inconsistency with the database approach
  • 29. Advantages of Database Processing
    • Integrity
      • An integrity constraint is a rule that must be followed by data in the database
        • Example: Not allowing a person’s age to be lower than zero
    • Security
      • The prevention of access to the database by unauthorized users
  • 30. Advantages of Database Processing
    • Increasing productivity
      • A good DBMS comes with many features that allow users to gain access to data without having to do any programming at all
    • Data independence
      • A property that allows the structure of a database to be changed without the programs that access the database having to change
  • 31. Figure 1.16 Disadvantages of Database Processing
  • 32. Disadvantages of Database Processing
    • DBMS size
      • DBMSs are large programs that occupy a large amount of disk space as well as internal memory
    • DBMS complexity
      • The complexity and breadth of the functions provided by a DBMS make it a complex product to use
  • 33. Disadvantages of Database Processing
    • Greater impact of a failure
      • A failure on the part of any one user that damages the database in some way may affect all the other users on the system
    • More difficult recovery
      • If the database is being updated by a large number of users, all updates must be redone since the time of its restoration
  • 34. History of Database Management
    • IBM developed the Generalized Update Access Method (GUAM) in 1964 for North American Rockwell, the prime contractor for the APOLLO project
    • GUAM was made available for the general public under the name Data Language/I (DL/I) in 1966
  • 35. History of Database Management
    • DL/I became the data management component for the Information Management System (IMS), which was the dominant DBMS for many years
    • In the mid-1960s, General Electric developed Integrated Data Store (I-D-S)
  • 36. History of Database Management
    • The COnference on DAta SYstems Languages (CODASYL) tackled the problem of providing standards for DBMSs in the late 1960s
    • In 1971, the CODASYL standards were presented to the American National Standards Institute (ANSI)
  • 37. History of Database Management
    • Throughout the 1970s, the relational model was the subject of intense research
    • The 1980s is when the first commercial relational DBMSs appeared
    • The 1980s saw the development of object-oriented database management systems (OODBMSs)
  • 38. Hierarchical and Network Databases
    • Four types of data models
      • Network
      • Hierarchical
      • Relational
      • Object-oriented
  • 39. Network Model
    • Perceived by the user as a collection of record types and relationships between these record types
    • I-D-S and other CODASYL systems are examples of DBMSs that conform to the network data model
  • 40. Figure 1.17 Network Database Structure
  • 41. Hierarchical Model
    • Perceived by the user as a collection of hierarchies, or trees
    • More restrictive structure than a network model
    • GUAM, DL/I, and IMS are examples of DBMSs that conform to the hierarchical model
  • 42. Figure 1.18 Hierarchical Database Structure