Organizing Data and Information C H A P T E R


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Organizing Data and Information C H A P T E R

  1. 1. Organizing Data and Information 5 C H A P T E R
  2. 2. The Hierarchy of Data <ul><li>Database </li></ul><ul><ul><li>Collection of data organized to meet users’ needs </li></ul></ul><ul><li>Database management system (DBMS) </li></ul><ul><ul><li>Software consisting of a group of programs that manipulate the database and provide an interface between the database and the application programs </li></ul></ul>
  3. 3. The Hierarchy of Data <ul><li>Data is generally organized in a hierarchy that begins with the smallest piece of data (a bit) and progresses through the hierarchy to a database. </li></ul>
  4. 4. The Hierarchy of Data <ul><li>Character </li></ul><ul><ul><li>Basic building block of information, represented by a byte (0,1) </li></ul></ul><ul><li>Field </li></ul><ul><ul><li>A name, number, or combination of characters that describes an aspect of a business activity </li></ul></ul>
  5. 5. The Hierarchy of Data <ul><li>Record </li></ul><ul><ul><li>Collection of related fields </li></ul></ul><ul><li>File </li></ul><ul><ul><li>Collection of related records </li></ul></ul><ul><li>Database </li></ul><ul><ul><li>Collection of integrated and related files </li></ul></ul>
  6. 6. Data Entities, Attributes, and Keys <ul><li>Entity </li></ul><ul><ul><li>Generalized class of people, places, or things for which data is collected, stored, and maintained </li></ul></ul><ul><li>Attribute </li></ul><ul><ul><li>Characteristic of an entity </li></ul></ul><ul><li>Data item </li></ul><ul><ul><li>Specific value of an attribute </li></ul></ul>
  7. 7. Data Entities, Attributes, and Keys <ul><li>Key </li></ul><ul><ul><li>A field or set of fields in a record that is used to identify the record </li></ul></ul><ul><ul><li>Primary key </li></ul></ul><ul><ul><ul><li>A field or set of fields that uniquely identifies the record </li></ul></ul></ul><ul><ul><li>Secondary key </li></ul></ul><ul><ul><ul><li>A field in a record that does not uniquely identify the record </li></ul></ul></ul>
  8. 8. Keys and Attributes Entities (records) Key field Attributes
  9. 9. The Traditional Approach to Data Management [Figure 5.3]
  10. 10. Flaws in the Traditional Approach <ul><li>Data redundancy </li></ul><ul><ul><li>Duplication of data in separate files </li></ul></ul><ul><li>Data integrity </li></ul><ul><ul><li>The degree to which the data in any one file is accurate </li></ul></ul><ul><li>Program-data dependence </li></ul><ul><ul><li>Potential for incompatible programs and data between applications </li></ul></ul>
  11. 11. The Database Approach to Data Management <ul><li>Data management in which a pool of related data is shared by multiple application programs </li></ul><ul><li>Rather than having separate data files, each application uses a collection of data that are either joined or related in the database. </li></ul>
  12. 12. The Database Approach to Data Management [Figure 5.4]
  13. 13. Advantages of the Database Approach <ul><li>Improved strategic use of corporate data </li></ul><ul><li>Reduced data redundancy </li></ul><ul><li>Improved data integrity </li></ul><ul><li>Easier modification and updating </li></ul><ul><li>Data and program independence </li></ul>
  14. 14. Advantages of the Database Approach <ul><li>Better access to data and information </li></ul><ul><li>Standardization of data access </li></ul><ul><li>A framework for program development </li></ul><ul><li>Better overall protection of the data </li></ul><ul><li>Shared data and information resources </li></ul>
  15. 15. Disadvantages of the Database Approach <ul><li>Relatively high cost of purchasing and operating a DBMS in a mainframe operating environment </li></ul><ul><li>Specialized staff </li></ul><ul><li>Increased vulnerability </li></ul>
  16. 16. Database Considerations <ul><li>Content </li></ul><ul><ul><li>What data is to be collected at what cost? </li></ul></ul><ul><li>Access </li></ul><ul><ul><li>What data is to be provided to which users when appropriate? </li></ul></ul>
  17. 17. Database Considerations <ul><li>Logical structure </li></ul><ul><ul><li>How is the data to be arranged so that it makes sense to a given user? </li></ul></ul><ul><li>Physical organization </li></ul><ul><ul><li>Where is the data to be physically located? </li></ul></ul>
  18. 18. Types of Database Design <ul><li>Logical design </li></ul><ul><ul><li>An abstract model of how the database should be structured and arranged to meet an organization’s information needs </li></ul></ul><ul><li>Physical design </li></ul><ul><ul><li>A model of how the data will be organized and located within the database </li></ul></ul>
  19. 19. Data Modeling and Entity-Relationship Diagrams <ul><li>Data model </li></ul><ul><ul><li>A map or diagram of entities and their relationships </li></ul></ul><ul><li>Enterprise data modeling </li></ul><ul><ul><li>Data modeling done at the level of the entire organization </li></ul></ul>
  20. 20. Entity-Relationship (ER) Diagrams <ul><li>Diagrams that use basic graphical diagrams to show the organization of and relationships between data </li></ul><ul><li>Relationships include: </li></ul><ul><ul><li>One-to-one (1:1) </li></ul></ul><ul><ul><li>One-to-many (1:N) </li></ul></ul><ul><ul><li>Many-to-many (N:M) </li></ul></ul>
  21. 21. An Entity-Relationship Diagram [Figure 5.5] An ER diagram for a customer ordering database Entities Relationship Attributes
  22. 22. Database Models <ul><li>Hierarchical (tree) models </li></ul><ul><li>Network models </li></ul><ul><li>Relational models </li></ul>
  23. 23. Hierarchical Database Model <ul><li>A model in which the data is organized in a top-down or inverted tree-like structure </li></ul><ul><li>[Figure 5.6] </li></ul>
  24. 24. Network Models <ul><li>An extension of the hierarchical model, in which a member may have many owners </li></ul><ul><li>[Figure 5.7] </li></ul>
  25. 25. Relational Models <ul><li>Data organized in tabular format (rows and columns) </li></ul><ul><ul><li>Relations: Two-dimensional tables into which data elements are placed </li></ul></ul><ul><ul><li>Tuple: Each row of a table </li></ul></ul><ul><ul><li>Attributes: Columns of the table </li></ul></ul><ul><ul><li>Domain: Values for attributes or columns </li></ul></ul>
  26. 26. Relational Models [Figure 5.8]
  27. 27. Data Manipulations <ul><li>Selecting </li></ul><ul><ul><li>Eliminating rows according to certain criteria </li></ul></ul><ul><li>Projecting </li></ul><ul><ul><li>Eliminating columns in a table </li></ul></ul>
  28. 28. Data Manipulations <ul><li>Joining </li></ul><ul><ul><li>Combining two or more tables </li></ul></ul><ul><li>Linking </li></ul><ul><ul><li>Joining tables that share at least one common data element </li></ul></ul>
  29. 29. Data Analysis and Normalization <ul><li>Data analysis </li></ul><ul><ul><li>Evaluation of data to uncover problems with the content of a database </li></ul></ul><ul><li>Anomalies </li></ul><ul><ul><li>Problems and irregularities in data </li></ul></ul><ul><li>Normalization </li></ul><ul><ul><li>Removing anomalies from a database </li></ul></ul>
  30. 30. Comparison of Database Models <ul><li>Hierarchical model </li></ul><ul><ul><li>Primary advantage: processing efficiency </li></ul></ul><ul><li>Network model </li></ul><ul><ul><li>More flexible than hierarchical models in terms of organizing data </li></ul></ul><ul><li>Relational database model </li></ul><ul><ul><li>Easier to control, more flexible, and more intuitive; by far the most widely used </li></ul></ul>
  31. 31. Database Characteristics <ul><li>Amount </li></ul><ul><ul><li>Database size depends on the number of records or files it contains </li></ul></ul><ul><li>Volatility </li></ul><ul><ul><li>A measure of the changes typically required in a given period of time </li></ul></ul><ul><li>Immediacy </li></ul><ul><ul><li>A measure of how rapidly changes must be made to data </li></ul></ul>
  32. 32. Database Management Systems <ul><li>Group of programs used as an interface between a database and application programs or a database and the user </li></ul><ul><li>Classified by the type of database model they support </li></ul><ul><ul><li>Hierarchical </li></ul></ul><ul><ul><li>Network </li></ul></ul><ul><ul><li>Relational </li></ul></ul>
  33. 33. Storing and Retrieving Data <ul><li>Logical access path </li></ul><ul><ul><li>Application requests data from the DBMS </li></ul></ul><ul><li>Physical access path </li></ul><ul><ul><li>DBMS accesses a storage device to retrieve the data </li></ul></ul><ul><li>[Figure 5.14] </li></ul>
  34. 34. Data Control <ul><li>Concurrency control </li></ul><ul><ul><li>Locks out simultaneous access to a record that is being updated or used by another program </li></ul></ul><ul><li>Schema </li></ul><ul><ul><li>The logical and physical structure of the data and relationships among the data in the database </li></ul></ul>
  35. 35. Providing a User View <ul><li>User view </li></ul><ul><ul><li>Portion of the database a user can access </li></ul></ul><ul><li>Subschema </li></ul><ul><ul><li>A file that contains a description of a subset of the database and identifies which users can perform modification on the data items in that subset </li></ul></ul><ul><ul><li>Developed to create different views </li></ul></ul>
  36. 36. The Use of Schemas and Subschemas [Figure 5.15]
  37. 37. Creating and Modifying the Database <ul><li>Data definition language (DDL) </li></ul><ul><ul><li>Collection of instructions and commands used to define and describe data and data relationships in a specific database </li></ul></ul><ul><li>[Figure 5.16] </li></ul>
  38. 38. Creating and Modifying the Database <ul><li>Data dictionary </li></ul><ul><ul><li>A detailed description of all data used in the database </li></ul></ul>[Figure 5.17]
  39. 39. Data Dictionary <ul><li>Provides a standard definition of terms and data elements </li></ul><ul><li>Assists programmers in designing and writing programs </li></ul><ul><li>Simplifies database modifications </li></ul>
  40. 40. Data Dictionary <ul><li>Helps achieve advantages of the database approach </li></ul><ul><ul><li>Reduced data redundancy </li></ul></ul><ul><ul><li>Increased data reliability </li></ul></ul><ul><ul><li>Faster program development </li></ul></ul><ul><ul><li>Easier modification of data and information </li></ul></ul>
  41. 41. Manipulating Data and Generating Reports <ul><li>Data Manipulation Language (DML) </li></ul><ul><ul><li>Contains the commands used to manipulate the database </li></ul></ul><ul><ul><li>Allows managers and other database users to access, modify, and make queries about data contained in the database to generate reports </li></ul></ul>
  42. 42. Structured Query Language (SQL) <ul><li>A standardized data manipulation language that has become an integral part of most relational database packages </li></ul>
  43. 43. Selecting a Database Management System <ul><li>Begins by analyzing database needs and characteristics </li></ul><ul><ul><li>Performance </li></ul></ul><ul><ul><li>Integration </li></ul></ul><ul><ul><li>Features </li></ul></ul><ul><ul><li>The vendor </li></ul></ul><ul><ul><li>Cost </li></ul></ul>
  44. 44. Emerging Database Trends <ul><li>Distributed databases </li></ul><ul><ul><li>Actual data may be spread across several smaller databases connected via telecommunications devices </li></ul></ul><ul><li>Replicated database </li></ul><ul><ul><li>Holds a duplicate set of frequently used data </li></ul></ul>
  45. 45. Distributed Database HCIA p223 HCIA, Inc. uses a distributed database to provide up-to-date information to their customers.
  46. 46. Data Warehouse <ul><li>A relational database management system designed specifically to support management decision making </li></ul><ul><li>[Figure 5.21] </li></ul>
  47. 47. Data Warehouse <ul><li>Data mart </li></ul><ul><ul><li>Subset of a data warehouse </li></ul></ul><ul><ul><li>Brings the data warehouse concept to small and medium-size businesses </li></ul></ul><ul><li>On-line analytical processing (OLAP) </li></ul><ul><ul><li>Consists of programs used to store and deliver data warehouse information </li></ul></ul><ul><li>Data mining </li></ul><ul><ul><li>Automated discovery of patterns and relationships in a data warehouse </li></ul></ul>
  48. 48. Open Database Connectivity (ODBC) <ul><li>Standards that help ensure that specific software can be used with any ODBC-compliant database </li></ul><ul><li>[Figure 5.22] </li></ul>
  49. 49. Object-Oriented Databases <ul><li>Databases that store data as objects, which contain both the data and the processing instructions needed to complete the database transaction </li></ul><ul><li>[Table 5.6] </li></ul>
  50. 50. Image, Hypertext, and Hypermedia Databases <ul><li>Image databases </li></ul><ul><ul><li>Store data in the form of images </li></ul></ul><ul><li>Hypertext databases </li></ul><ul><ul><li>Allow users to search and manipulate alphanumeric data in an unstructured way </li></ul></ul><ul><li>Hypermedia databases </li></ul><ul><ul><li>Allow businesses to search and manipulate multimedia forms of data </li></ul></ul>
  51. 51. Spatial Data Technology <ul><li>Involves the use of an object-relational database </li></ul><ul><li>Stores and accesses data according to the locations it describes </li></ul><ul><li>Permits spatial queries and analysis </li></ul>
  52. 52. Aspects of Database Administration <ul><li>Overall design and coordination of the database </li></ul><ul><li>Development and maintenance of schemas and subschemas </li></ul><ul><li>Development and maintenance of the data dictionary </li></ul><ul><li>Implementation of the DBMS </li></ul>
  53. 53. Aspects of Database Administration <ul><li>System and user documentation </li></ul><ul><li>User support and training </li></ul><ul><li>Overall operation of the DBMS </li></ul><ul><li>Testing and maintaining the DBMS </li></ul><ul><li>Establishing emergency or failure-recovery procedures </li></ul>
  54. 54. Database Use, Policies, and Security <ul><li>What data should users have direct access to? </li></ul><ul><li>Under what circumstances can data be transferred from a PC or small computer system to the large mainframe system (uploading)? </li></ul>
  55. 55. Database Use, Policies, and Security <ul><li>Under what circumstances can data be transferred from a mainframe system to PCs or small computer system (downloading)? </li></ul><ul><li>What procedures are needed to guarantee proper database use? </li></ul>