1 / 40

Chapter 3: Data Modeling

Chapter 3: Data Modeling. Introduction An Overview of Databases Steps in Developing a Database Using Resources, Events and Agents Model Normalization. Introduction. Uses of a modern AIS Systematically record data Provide convenient and useful formats Easy access to information.

carlawood
Download Presentation

Chapter 3: Data Modeling

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Chapter 3:Data Modeling • Introduction • An Overview of Databases • Steps in Developing a Database Using Resources, Events and Agents Model • Normalization

  2. Introduction • Uses of a modern AIS • Systematically record data • Provide convenient and useful formats • Easy access to information

  3. Data Stores-Specific Diagrams • Included on both Flowcharts and DFDs • There are also rules related to data stores. For example • Can a customer have more than one address? • Can an address belong to more than one customer?

  4. What is a Database? • Collection of organized data • Used by many different computer applications • Manipulated by database management systems (DBMS)

  5. Significance of a Database • Critical information • Volume • Distribution • Privacy • Irreplaceable data • Need for accuracy • Internet uses

  6. Storing Data in Databases • Data must be stored and organized systematically • Three important concepts: • Data hierarchy • Record structures • Database keys

  7. Data Hierarchy • Data organization in ascending order: • Data field • Record • File • Database

  8. Record Structures • Data fields in each record of a database table • Structure is usually fixed • Example

  9. Database Keys • Primary Key • Unique to each record • Foreign Keys • Enable referencing of one or more records • Matches primary key of related table

  10. Records Combined Into Report

  11. Additional Database Issues • Administration • Database Administrator • Documentation • Includes a variety of descriptions • Structures, Contents, Security Features • Data Dictionary • Metadata

  12. Data Dictionary Example

  13. Additional Database Issues • Data Integrity • Data Integrity controls • Designed by database developers • Processing Accuracy and Completeness • Transaction controls • Ensures accurate transaction processing

  14. Additional Database Issues • Concurrency • Concurrency controls • Prevent multi-user access at same time • Backup and Security • Ability to recreate data • Prevent unauthorized access • View controls

  15. Study Break #1 • The part of the data hierarchy that represents one instance of an entity is a: • Field • Record • File • Database

  16. REA(L) Model • Resources • Organization’s assets • Events • Activities associated with a business processes • Agents • People associated with business activities • Location

  17. Steps in DevelopingDatabases with REA • Identify Business and Economic Events • Identify Entities • Identify Relationships Among Entities

  18. Steps in DevelopingDatabases with REA • Create Entity-Relationship Diagrams • Identify Attributes of Entities • Convert E-R Diagrams into Database Tables

  19. Identify Events and Entities • Types of Events • Business • Economic • Types of Database Entities • Entities • Agents • Resources

  20. Entity Examples

  21. Identify RelationshipsAmong Entities • Types of Relationships • Direct relationship • Indirect relationship • Cardinalities • Nature of relationships among entities

  22. Cardinality Relationships • Notations • One-to-one (1:1) • One-to-many (1:N) • Many-to-many (N:M) • Purpose • Occurrence of one entity • Associated with occurrence of one event of another entity • Examples of each (1:1, 1:N, N:M)

  23. Cardinality Relationships

  24. Entity-Relationship Diagram • Purpose • Diagram entities • Relationships among entities • Structure • Rectangles represent entities • Connecting lines represent relationships

  25. E-R Diagram Example

  26. Relationship Tables • Provide greater flexibility • Need for Relationship Tables • Many-to-many relationships • Linking tables with foreign keys

  27. Relationship Tables

  28. Schematic of Database Tables

  29. Normalization • Normalization • Methodology ensuring attributes are stored in most appropriate tables • Design promotes accuracy • Avoids redundancy of data storage • Levels • First normal form • Second normal form • Third normal form

  30. Unnormalized Data

  31. First Normal Form • In First Normal Form (1 NF) when: • All data fields are singular • Each attribute has one value • Problems • Data redundancy • Insertion anomaly • Deletion anomaly

  32. First Normal Form Example

  33. Anomalies

  34. Second Normal Form • In Second Normal Form (2 NF) when: • It is in 1 NF • All data items depend on primary record key (i.e., no partial dependencies) • Benefits • More efficient design • Eliminates data redundancy

  35. Second Normal Form Example

  36. Third Normal Form • In Third Normal Form (3 NF) when: • It is in 2 NF • Does not contain transitive dependencies • Data field A does not determine data field B • Ultimate Goal • Create database in 3 NF

  37. Third Normal Form Example

  38. Study Break #5 • A database is in third normal form (3NF) if it is second normal form and: • All the data attributes in a record are well defined • All the data attributes in a record depend on the record key • The data contain to transitive dependencies • The data can be stored in two or more separate tables

More Related