1. Entity Relationship Diagrams Don Archer

2. Entity Relationship Diagram  ERDs – depicts data in terms of the entities and relationships described by the data.

3. Entity Definition  Entity - is a person, place, thing, or event of importance to the organization. Anything that can be a noun can be an entity.  Entity Occurrence - One individual instance of a type of entity - the set of data describing an instance of an entity.

4. Identifying Entities Identify the nouns in the conversation: Students may enroll in 12 courses. Classes are scheduled during 6 sessions throughout the year and are identified by sections. Each class may contain 18 students. Students may have several registrations for these classes that are held at 6 locations. Qualified faculty are assigned to various sections of of the classes. Not all faculty are qualified to teach all courses.

5. Identifying Entities Identify the nouns in the conversation: STUDENTs may enroll in 12 COURSEs. CLASSes are scheduled during 6 SESSIONs throughout the YEAR and are identified by SECTIONs. Each CLASS may contain 18 STUDENTs. STUDENTs may have several REGISTRATIONs for these CLASSes that are held at 6 LOCATIONs. QUALIFIED FACULTY are assigned to various SECTIONs of of the CLASSes. Not all FACULTY are qualified to teach all COURSEs.

8. Identifying Relationships Identify the verbs in the conversation: STUDENTs may enroll in 12 COURSEs. Classes are scheduled during 6 SESSIONs throughout the YEAR and are identified by SECTIONs. Each class may contain 18 students. Students may have several REGISTRATIONs for these classes that are held at 6 LOCATIONs. QUALIFIED FACULTY are assigned to various sections of of the classes. Not all FACULTY are qualified to teach all courses.

9. Identifying Relationships Identify the verbs in the conversation: Students may ENROLL in 12 courses. Classes are SCHEDULED during 6 sessions throughout the year and are IDENTIFIED by sections. Each class may CONTAIN 18 students. Students may HAVE several registrations for these classes that are HELD at 6 locations. Qualified faculty are ASSIGNED to various sections of of the classes. Not all faculty are QUALIFIED to teach all courses.

10. Identifying Entities & Relations

11. Identifying Entities Many-to-many

12. Identifying Entities Enrolls in Consists of

13. Is This Correct???

14. NO! Many-to-many This is a many-to-many relationship

15. How do you fix a M:M relation?

16. Associative Entity

17. Refinements

20. Location & Faculty

24. Recursive

25. Business rules  Each STUDENT may HAVE one or more CLASS REGISTRATIONS.  Each CLASS REGISTRATION must be ASSIGNED to one & only one STUDENT.  Each CLASS may HAVE one or more CLASS REGISTRATIONs.  Each CLASS REGISTRATION must BE FOR one & only one CLASS.  Each COURSE may BE ASSIGNED to one or more SCHEDULED CLASSes.  Each SCHEDULED CLASS must CONSIST on one & only one COURSE.

26. Business rules  Each LOCATION may be ASSIGNED one or more SCHEDULED CLASSes.  Each SCHEDULED CLASS must BE ASSIGNED to one & only one LOCATION.  Each YEAR may be ASSIGNED one or more SCHEDULED CLASSes.  Each SCHEDULED CLASS must BE ASSIGNED to one & only one YEAR.  Each SECTION may be ASSIGNED one or more SCHEDULED CLASSes.  Each SCHEDULED CLASS must BE ASSIGNED to one & only one SECTION.

27. Business rules  Each FACULTY may ADVISE one or more STUDENTs.  Each STUDENT must be ADVISED BY one & only one ADVISOR.  Each QUALIFIED FACULTY must be ASSIGNED to one & only one COURSE.  Each COURSE may be QUALIFIED by one or more QUALIFIED FACULTY.  Each QUALIFIED FACULTY must CONSIST of one & only one FACULTY.  Each FACULTY may be QUALIFIED for one or more QUALIFIED FACULTY positions.

28. Visio

29. Other Questions?