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Database Management

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  1. Database Management Chapter 4

  2. Chapter Objectives • Describe why databases have become so important to modern organizations • Describe what database and DBMS are and how they work • Explain four emerging database trends: • Client-server computing • Object-oriented databases • Data mining • Integrating Web applications

  3. Database Management for Strategic Advantage • We live in the Information Age • Information used to make organizations more productive and competitive • Databases used to support business operations

  4. Databases Before the Use of Computers • Data kept in books, ledgers, card files, folders, and file cabinets • Long response time • Labor-intensive • Often incomplete or inaccurate

  5. The Database Approach • Database-management system (DBMS) • Interact with the data in databases • Entity: something you collect data about • Field: one characteristic of an entity • Record: collection of fields that describe one occurrence of an entity • Entities stored in tables • One record per row • One field per column

  6. Sample Data Table

  7. The Database Approach • DBMS replaced file processing approach • Reduced data redundancy • Reduced program dependence • Databases typically consist of several tables • Tables can be linked together

  8. Key Database Issuesand Activities • Entering and Querying Data • Creating Database Reports

  9. Entering and Querying Data • Use a form for data entry • Use queries to retrieve information • Structured Query Language (SQL) • Query by example (QBE)

  10. Preprinted Form

  11. Computer-Based Form

  12. QBE Grid

  13. Creating Database Reports • Report • A compilation of data organized and produced in printed format • DBMS packages include a report writer • Graphics can be added • Can be automatically updated by linking to data

  14. Sample Quarterly Sales Report

  15. Data Structure • Data model • A representation of the entities and their relationships • Primary key • An attribute or combination of attributes • Uniquely identifies each record

  16. Data Type • Each field is assigned a type • Text, number, date, etc. • Data types help the DBMS • Organize and sort the data • Do calculations • Allocate space • Data dictionary • A repository of information about the data • Key fields, data types, valid values, etc.

  17. Database Management Systems Approaches • Models of the relationship between entities in a database • Hierarchical • Network • Relational

  18. The Hierarchical Model • Models entities in a parent-child relationship • One-to-many relationships • Parent entities can have many child records • Each child can have only one parent • Inadequate model for many databases • Not always clear which entity is the parent and which is the child

  19. The Hierarchical Model

  20. The Network Model • More flexible than the hierarchical model • Many-to-many relationships • Allows multiple children and parents • Complex databases become too cumbersome with this model

  21. The Network Model

  22. The Relational Model • Views entities as two-dimensional tables • Records are rows • Attributes are columns • Tables can be linked • Supports one-to-many, many-to-many, and one-to-one relationships

  23. The Relational Model

  24. Normalization • A technique used to make complex databases more efficient • Break one large table into several smaller tables • Eliminates all repeating groups in records • Eliminates redundant data

  25. Redundant Data

  26. Normalized Data

  27. Associations • Relationships among the entities in the data structures • Three types • One-to-one • One-to-many • Many-to-many • Relationships set by placing primary key from one table as foreign key in another • Creates “acceptable” redundancy

  28. Recent Developments Affecting Database Design and Use • Databases and Client-Server Computing • Server holds the actual database • Clients hold software to work with the database • Object-Oriented Databases (OODBs) • Treat tables, queries, etc., as reusable objects

  29. Client/Server Database

  30. Recent Developments Affecting Database Design and Use • Data Mining (On-Line Analytical Processing) • Drill down from summary data to detailed data • Data Warehouses/Data Marts • Integrates many large databases into one repository • Linking Web Site Applications to Organizational Databases • Users have Web view to organizational database • Improves customer contact and service • Adds security as a concern

  31. Effective Management of Databases • Database Administrator (DBA) • Responsible for the development and management of an organization’s databases • Works with systems analysts on design • Works with users and managers on managerial and organizational issues • Responsible for implementing security features

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