Exam-style question
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A training centre has learners and workshops. Each learner may attend several workshops, and each workshop may be attended by several learners. For every attendance, the centre records the attendance date and whether the learner was present. Produce a conceptual data model with entity descriptions and explain how the entity relationship diagram should represent the many-to-many association.
Model answer
What a good answer should say
- Learner (LearnerID, LearnerName, LearnerEmail) Workshop (WorkshopID, WorkshopTitle, WorkshopDate) Attendance (AttendanceID, AttendanceDate, Present, LearnerID, WorkshopID) The ERD should show Learner connected to Attendance and Workshop connected to Attendance.
- Attendance represents one learner attending one workshop, so Attendance is the entity that stores AttendanceDate and Present.
- LearnerID, WorkshopID and AttendanceID are identifiers for their respective entities and would be underlined or otherwise identified as entity identifiers.
- The diagram therefore models the association through Attendance rather than placing a list of workshops in Learner or a list of learners in Workshop.
Explanation
Why this works
The requirements describe a many-to-many association between Learner and Workshop. Attendance is an additional entity that represents each occurrence of that association and provides a place for attributes that describe the occurrence, such as the date and presence status.
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