Lecture 7 (Week 7) - Cardinality & modality.pptx

Database Management Systems. Cardinality and Modality

1. “Database Management Systems” CS-222 Lecture 33 “Cardinality & modality” Dr. Muhammad Muneer Umar By: Lecturer in Computer Science Institute of Computing KUST, Pakistan

2. Consider some cases An employee can have many children A student must have exactly one father Many teachers are teaching many subjects Course: Database Management Systems (CS222) || Instructor: Dr. Muneer Umar, Lecturer. Institute of Computing, KUST || Email: [email protected] Topic: Cardinality & Modality

3. Agenda Revision of ERD Cardinality and Modality How to read cardinalities Sample Cases Course: Database Management Systems (CS222) || Instructor: Dr. Muneer Umar, Lecturer. Institute of Computing, KUST || Email: [email protected] Topic: Cardinality & Modality

4. -Semantic Data Model -Graphical representation of the conceptual database design Course: Database Management Systems (CS222) || Instructor: Dr. Muneer Umar, Lecturer. Institute of Computing, KUST || Email: [email protected] Topic: Cardinality & Modality ERD ( Entity Relationship Diagram)

5. -Semantic Data Model -Graphical representation of the conceptual database design Three major constructs: Entity Attributes Relationships Course: Database Management Systems (CS222) || Instructor: Dr. Muneer Umar, Lecturer. Institute of Computing, KUST || Email: [email protected] Topic: Cardinality & Modality ERD ( Entity Relationship Diagram)

6. Entity Entity Type Entity Instance Entity Set Course: Database Management Systems (CS222) || Instructor: Dr. Muneer Umar, Lecturer. Institute of Computing, KUST || Email: [email protected] Topic: Cardinality & Modality

7. STUDENT LOCATION Entity-Entity Type Course: Database Management Systems (CS222) || Instructor: Dr. Muneer Umar, Lecturer. Institute of Computing, KUST || Email: [email protected] Topic: Cardinality & Modality

8. STUDENT LOCATION Name … ZIP Ali --- 26000 Ahmed --- 25000 ZIP City Province Country 26000 Kohat KPK Pakistan 25000 Peshawar KPK Pakistan 41000 Islamabad Pakistan Course: Database Management Systems (CS222) || Instructor: Dr. Muneer Umar, Lecturer. Institute of Computing, KUST || Email: [email protected] Topic: Cardinality & Modality Entity-Entity Instance & Set

9. STUDENT 2. Attributes Name FName Age Skills Skills Session Start End Course: Database Management Systems (CS222) || Instructor: Dr. Muneer Umar, Lecturer. Institute of Computing, KUST || Email: [email protected] Topic: Cardinality & Modality

10. STUDENT LOCATION Name … ZIP Ali --- 26000 Ahmed --- 25000 Khan --- 26000 ZIP City Province Country 26000 Kohat KPK Pakistan 25000 Peshawar KPK Pakistan 54000 Lahore Punjab Pakistan 72206 Tehran Tehran Iran 3. Relationships Course: Database Management Systems (CS222) || Instructor: Dr. Muneer Umar, Lecturer. Institute of Computing, KUST || Email: [email protected] Topic: Cardinality & Modality

11. STUDENT LOCATION Name … ZIP Ali --- 26000 Ahmed --- 25000 Khan --- 26000 ZIP City Province Country 26000 Kohat KPK Pakistan 25000 Peshawar KPK Pakistan 54000 Lahore Punjab Pakistan 72206 Tehran Tehran Iran Course: Database Management Systems (CS222) || Instructor: Dr. Muneer Umar, Lecturer. Institute of Computing, KUST || Email: [email protected] Topic: Cardinality & Modality 3. Relationships

12. Agenda Revision of ERD Cardinality and Modality How to read cardinalities Sample Cases Course: Database Management Systems (CS222) || Instructor: Dr. Muneer Umar, Lecturer. Institute of Computing, KUST || Email: [email protected] Topic: Cardinality & Modality

13. Cardinality  Maximum possible associations 1 OR many Modality  Minimum possible associations 1 OR Zero Course: Database Management Systems (CS222) || Instructor: Dr. Muneer Umar, Lecturer. Institute of Computing, KUST || Email: [email protected] Topic: Cardinality & Modality

14. STUDENT LOCATION Name … ZIP Ali --- 26000 Ahmed --- 25000 Khan --- 26000 ZIP City Province Country 26000 Kohat KPK Pakistan 25000 Peshawar KPK Pakistan 54000 Lahore Punjab Pakistan 72206 Tehran Tehran Iran Modality Cardinality Course: Database Management Systems (CS222) || Instructor: Dr. Muneer Umar, Lecturer. Institute of Computing, KUST || Email: [email protected] Topic: Cardinality & Modality

15. Cardinality and Modality Cardinality and Modality work together to define the relationship Cardinality indicates the maximum number of times an instance in one entity can be associated with instances in the related entity Modality indicates the minimum number of times an instance in one entity can be associated with an instance in the related entity Cardinality and Modality are both shown on the relationship line by symbols Course: Database Management Systems (CS222) || Instructor: Dr. Muneer Umar, Lecturer. Institute of Computing, KUST || Email: [email protected] Topic: Cardinality & Modality

16. Agenda Revision of ERD Cardinality and Modality How to read cardinalities Sample Cases Course: Database Management Systems (CS222) || Instructor: Dr. Muneer Umar, Lecturer. Institute of Computing, KUST || Email: [email protected] Topic: Cardinality & Modality

17. Reading Modality and Cardinality from Zero to Many from One to Many from One to One i.e., one and only one from Zero to One Modality and cardinality are combined (two at a time) in these ways: Course: Database Management Systems (CS222) || Instructor: Dr. Muneer Umar, Lecturer. Institute of Computing, KUST || Email: [email protected] Topic: Cardinality & Modality

18. Student Seat fills Course Instructor teaches Course Student Registers for Transcript Student has Left to right: a seat is filled by exactly one student Right to left: a student fills exactly one seat Left to right: a student has one or more transcripts Right to left: a transcript has one student Left to right: a student registers for one or more courses Right to left: a course is registered by one or more students Left to right: an instructor teaches zero to many courses Right to left: a course is taught by exactly one instructor Reading Cardinality and Modality Course: Database Management Systems (CS222) || Instructor: Dr. Muneer Umar, Lecturer. Institute of Computing, KUST || Email: [email protected] Topic: Cardinality & Modality

19. Student Seat fills Course Instructor teaches Course Student Registers for Left to right: one to one, 1:1 Right to left: one to one, 1:1 Left to right: one to many, 1:M Right to left: many to one, M:1 Left to right: many to many, M:M Right to left: many to many, M:M Left to right: one to many, 1:M Right to left: many to one, M:1 Reading Cardinality Transcript Student has Course: Database Management Systems (CS222) || Instructor: Dr. Muneer Umar, Lecturer. Institute of Computing, KUST || Email: [email protected] Topic: Cardinality & Modality

20. Cardinalities and Modalities Modalities can also be called as: Mandatory Cardinalities = The entity must participate in another entity. Optional Cardinalities = The entity has the option to participate in another entity. Course: Database Management Systems (CS222) || Instructor: Dr. Muneer Umar, Lecturer. Institute of Computing, KUST || Email: [email protected] Topic: Cardinality & Modality

21. Cardinalities and Modalities Cardinalities and modalities can also be defined as: Maximum Cardinality: One or many Minimum Cardinality: Required or not. Course: Database Management Systems (CS222) || Instructor: Dr. Muneer Umar, Lecturer. Institute of Computing, KUST || Email: [email protected] Topic: Cardinality & Modality

22. Agenda Revision of ERD Cardinality and Modality How to read cardinalities Sample Cases Course: Database Management Systems (CS222) || Instructor: Dr. Muneer Umar, Lecturer. Institute of Computing, KUST || Email: [email protected] Topic: Cardinality & Modality

23. EMPLOYEE VEHICLE Name … VID Ali --- IDE403 Ahmed --- Khan --- EGA911 Akbar CSS900 Burhan ACX907 VID Type Model Maker IDE403 Sedan 2017 Toyota ACX907 Hatchback 2013 Suzuki EGA911 SUV 2009 Toyota CSS900 Sedan 2011 Toyota Is it Correct?? Course: Database Management Systems (CS222) || Instructor: Dr. Muneer Umar, Lecturer. Institute of Computing, KUST || Email: [email protected] Topic: Cardinality & Modality

24. EMPLOYEE VEHICLE Name … VID Ali --- IDE403 Ahmed --- Khan --- EGA911 Akbar CSS900 Burhan ACX907 VID Type Model Maker IDE403 Sedan 2017 Toyota ACX907 Hatchback 2013 Suzuki EGA911 SUV 2009 Toyota CSS900 Sedan 2011 Toyota Now it is Correct  Course: Database Management Systems (CS222) || Instructor: Dr. Muneer Umar, Lecturer. Institute of Computing, KUST || Email: [email protected] Topic: Cardinality & Modality

25. EMPLOYEE CHILDREN Name … CID Ali --- C001 Ali --- C002 Khan --- C003 Akbar Burhan C004 CID NAME --- C00 1 Asad C00 2 Ayesha C00 3 Farooq C004 Khalil ??? Course: Database Management Systems (CS222) || Instructor: Dr. Muneer Umar, Lecturer. Institute of Computing, KUST || Email: [email protected] Topic: Cardinality & Modality

26. EMPLOYEE CHILDREN Name … CID Ali --- C001 Ali --- C002 Khan --- C003 Akbar Burhan C004 CID NAME --- C00 1 Asad C00 2 Ayesha C00 3 Farooq C004 Khalil ??? Course: Database Management Systems (CS222) || Instructor: Dr. Muneer Umar, Lecturer. Institute of Computing, KUST || Email: [email protected] Topic: Cardinality & Modality

27. SUMMARY REVISION OF ERD Cardinality  Maximum cases (1 or many) Modality  Minimum Cases (0 or 1) Mandatory Cardinality  Modality =1 Optional Cardinality  Modality = 0 Possible Cases  1:1, 1:M, M:M (can be read from both direction)

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