information systems

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information systems

  1. 1. INFORMATION SYSTEM Lecture # 12
  2. 2. Principles ofInformation Systems (Eighth Edition) CHAPTER 5 (CONTINUED) ORGANIZING DATA AND INFORMATION
  3. 3. DATA MODELING AND THERELATIONAL DATABASE MODEL When building a database, an organization must consider: Edition Principles of Information Systems, Eighth  Content: What data should be collected and at what cost?  Access: What data should be provided to which users and when?  Logical structure: How should data be arranged so that it makes sense to a given user?  Physical organization: Where should data be physically located? 3
  4. 4. DATA MODELING Building a database requires two types of designs  Logical design: abstract model of how the data should be structured and arranged to meet an Edition Principles of Information Systems, Eighth organization’s information needs  Physical design: starts from the logical database design and fine-tunes it for performance and cost considerations 4
  5. 5. DATA MODELING (CONTINUED) Data model: diagram of data entities and their relationships Edition Principles of Information Systems, Eighth Entity-relationship (ER) diagrams: data models that use basic graphical symbols to show the organization of and relationships between data 5
  6. 6. DATA MODELING (CONTINUED) Figure 5.4: An Entity-Relationship (ER) Diagram for a Customer Order DatabasePrinciples of Information Systems, Eighth Edition 6
  7. 7. THE RELATIONAL DATABASEMODEL Relational model: describes data in which all data elements are placed in two-dimensional tables, called relations, that are the logical Edition Principles of Information Systems, Eighth equivalent of files  Each row of a table represents a data entity  Columns of the table represent attributes  Domain: allowable values for data attributes 7
  8. 8. THE RELATIONAL DATABASEMODEL (CONTINUED) Edition Principles of Information Systems, Eighth Figure 5.5: A Relational Database Model 8
  9. 9. THE RELATIONAL DATABASEMODEL (CONTINUED) Selecting: eliminates rows according to certain criteria Edition Principles of Information Systems, Eighth Projecting: eliminates columns in a table Joining: combines two or more tables Linking: manipulating two or more tables that share at least one common data attribute to provide useful information and reports 9
  10. 10. THE RELATIONAL DATABASEMODEL (CONTINUED) Edition Principles of Information Systems, EighthFigure 5.6: A Simplified ER Diagram Showing the Relationship Between the Manager, Department, and Project Tables 10
  11. 11. THE RELATIONAL DATABASE MODEL(CONTINUED) Edition Principles of Information Systems, Eighth 11 Figure 5.7: Linking Data Tables to Answer an Inquiry
  12. 12. THE RELATIONAL DATABASE MODEL(CONTINUED) Data cleanup: process of looking for and fixing inconsistencies to ensure that data is accurate and complete  Eliminate redundancies and anomaliesPrinciples of Information Systems, Eighth Edition 12
  13. 13. THE RELATIONAL DATABASE MODEL(CONTINUED) Edition Principles of Information Systems, Eighth Table 5.3: Fitness Center Dues 13
  14. 14. THE RELATIONAL DATABASE MODEL(CONTINUED) Table 5.4: Fitness Center Members Table 5.5: Dues PaidPrinciples of Information Systems, Eighth Edition 14
  15. 15. DATABASE MANAGEMENT SYSTEMS (DBMSS) Creating and implementing the right database system ensures that the database will support both Edition Principles of Information Systems, Eighth business activities and goals DBMS: a group of programs used as an interface between a database and application programs or a database and the user 15
  16. 16. OVERVIEW OF DATABASE TYPES Flat file  Simple database program whose records have no relationship to one another Edition Principles of Information Systems, Eighth Single user  Onlyone person can use the database at a time  Examples: Access, FileMaker, and InfoPath Multiple user  Allowsdozens or hundreds of people to access the same database system at the same time  Examples: Oracle, Sybase, and IBM 16
  17. 17. PROVIDING A USER VIEW Schema: description of the entire database  Typically used by large database systems to define tables and other database features associated with a Edition Principles of Information Systems, Eighth person or user A DBMS can reference a schema to find where to access the requested data in relation to another piece of data 17
  18. 18. CREATING AND MODIFYING THEDATABASE Data definition language (DDL): collection of instructions and commands used to define and describe data and relationships in a specific Edition Principles of Information Systems, Eighth database  Allows the database’s creator to describe the data and relationships that are to be contained in the schema Data dictionary: detailed description of all the data used in the database 18
  19. 19. CREATING AND MODIFYING THEDATABASE (CONTINUED) Figure 5.10: Using a Data Definition Language to Define a SchemaPrinciples of Information Systems, Eighth Edition 19
  20. 20. CREATING AND MODIFYING THEDATABASE (CONTINUED) Figure 5.11: A Typical Data Dictionary EntryPrinciples of Information Systems, Eighth Edition 20
  21. 21. STORING AND RETRIEVING DATA When an application program requests data from the DBMS, the application program follows a logical access path Edition Principles of Information Systems, Eighth 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 21
  22. 22. STORING AND RETRIEVING DATA(CONTINUED) Figure 5.12: Logical and Physical Access PathsPrinciples of Information Systems, Eighth Edition 22
  23. 23. MANIPULATING DATA ANDGENERATING REPORTS Data manipulation language (DML): commands that manipulate the data in a database Edition Principles of Information Systems, Eighth Structured Query Language (SQL)  Adopted by the American National Standards Institute (ANSI) as the standard query language for relational databases Once a database has been set up and loaded with data, it can produce reports, documents, and other outputs 23
  24. 24. MANIPULATING DATA AND GENERATINGREPORTS (CONTINUED) Table 5.6: Examples of SQL CommandsPrinciples of Information Systems, Eighth Edition 24

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