1. IT 21103/41103 System Analysis & Design

2. Chapter 04 Data Modeling

3. Concerned with the data flow of an organization

4. Data Modeling Focuses on Data Only

5. Data Modeling Data Attributes NameSizeType

6. Data Modeling Name Unique Indentifer

7. Data Modeling Size Amount of space required to hold the data

8. Data Modeling Type How the computer stores the data

9. Data Modeling Data Structures Specific organizational strategies for associating data elements

10. Data Modeling Examples:Receipts File Folders

11. Data Modeling Computer Data Structures Mimic the real-world Helps the analyst link data to the new system

12. Data Modeling Data Streams Series of characters that form a command or represent specific data values in a program

13. Data Modeling File Organized data structure with a specific format

14. Data Modeling Master File Identifies an individual person or thing in the organization

15. Data Modeling Transaction File Data collection that represents a specific event or activity

16. Data Modeling Database Collection of files containing data about the current operations of an organization

17. Data Modeling Data Warehouse Collection of files about the past operations of an organization

18. Data Modeling Relational Databases Collection of data tied together by common fields

19. Data Modeling Common Fields Primary Key Field(s) Foreign Key Field(s) - Create Relationships

20. Data Modeling Entity-Relationship Diagram - ERD

21. ERD ► The Entity-Relationship Approach  Represents reality using well-defined graphics and rules ► Basic building blocks are “things” (entities) and relationships Member Animal M 1 Adopts

22. ERD ► Advantages  Theoretical foundation (Set Theory)  Good for communication  Build E-R Model, then translate to any type of RDBMS ► Disadvantages  Different (yet another new thing to learn)  Must translate to the relational model

23. ERD ► Entity-Relationship Model: Basic Concepts  Entity ► Thing, Object, Concept of interest to the enterprise ► Each occurrence can be uniquely identified

24. ERD ► Entity-Relationship Model: Basic Concepts  Attribute ► Property of an entity ► Column

25. ERD ► Entity-Relationship Model: Basic Concepts  Relationship ► Association between two (or more) entities

26. ERD ► Entity-Relationship Model: Basic Concepts  Entity Identifier ► Attribute(s) whose value uniquely identifies an entity ► Primary Key

27. ERD ► What is an Entity?  Physical entity types ► Person ► Building ► Machine ► Book ► Usually Singular

28. ERD ► What is an Entity?  Conceptual entity types ► Contract ► Account ► Order ► Course

29. ERD ► What is an Entity?  Event entity types ► Transaction ► Shipment ► Reservation ► Phone Call ► Seminar Offering

30. ERD ► Entity-Relationship Model: Diagrams  Example:  Soft Rectangle represents entities ► Noun ► Singular  Connecting Line represents relationships ► Verb Member Animal Adopts

31. ERD ► Relationships have Characteristics  A relationship has Cardinality (Degree) One-to-OneOne-to-Many Many-to-Many

32. ERD ► Each entity’s participation is Mandatory or Optional ► Cardinality & Optionality are based on business rules Mandatory Optional

33. ERD ► One:One Relationship  One Member adopts one animal  One Animal is adopted by one member Member Animal Adopts

34. ERD ► One:Many relationship  One member adopts one animal  One animal is adopted by many members Member Animal Adopts

35. ERD ► Many:Many relationship  One member adopts many animals  One animal is adopted by many members Member Animal Adopts

36. ERD ► Optionality: Participation in a Relationship Zoo Employee Animal Cares for

37. ERD ► Mandatory  Every instance of the entity MUST participate in the relationship  Example: ► Every animal is cared for by at least one employee

38. ERD ► Optional  An instance of the entity CAN participate in the relationship  Example: ► Some employees do not take care of animals

39. ERD ► Drawing an E-R Diagram  Identify the entities  Write (make up) a few attributes for each entity  Designate the unique identifier (PK)  Identify the relationship (FK goes on the many side)  Show cardinality and optionality for each relationship

40. ERD ► E-R Modeling Exercise:  A Seminar Company ► A seminar company offers more than 100 different courses  Each course has a unique course number and a title ► The company schedules thousands of seminars annually  Each seminar is the presentation of one specific course  A seminar is either public or on-site

42. ERD ► E-R Model:  Entities ► Course  Course # (PK)  Course Title  Duration  Author

43. ERD ► E-R Model:  Entities ► Seminar  Seminar # (PK)  Date  Place  Type ► Public ► On-site  Course # (FK)

44. ERD ► E-R Model: COURSE SEMINAR Presented by

45. ERD ► E-R Modeling Exercise:  A Personnel Database ► A company has four divisions ► Each employee works for a department ► Each department reports to one of the divisions

46. ERD ► E-R Model:  Entities ► Division  Division #  Division Name

47. ERD ► E-R Model:  Entities ► Employee  Employee #  Employee Name  Dept # (FK)

48. ERD ► E-R Model:  Entities ► Department  Dept #  Dept Name  Div # (FK)

49. ERD ► E-R Model: DIVISIONDEPARTMENT Reports to EMPLOYEE Works for

50. Relational Database Theory ► E-R Modeling Exercise:  A Supplier-Parts Database ► A company purchases many parts from its suppliers  Each part has only one supplier ► A supplier can supply zero, one, or many parts  One _____(can/must) _____ (one and only one/one or more) ______

52. Relational Database Theory ► E-R Model: SUPPLIER PARTS Supplies

53. ERD Assignment 04 Page 117