Can a set of the data requirements be correctly modelled by two or more dissimilar ER diagrams? Elucidate your answer. You might use a small illustration, if you think it will assist your explanation.
Map the following E-R model in the relational schema, concisely outlining the procedure and clearly showing the relation names, primary keys, attributes and foreign keys.
Draw the ER diagram for following description. Demonstrate only the entity types (disregard the attributes), the relationships between them and multiplicity of each relationship.
A company specialises on IT training. At the time being, the company has 20 instructors, offers 30 courses and can handle the maximum number of 600 trainees. But, these numbers might rise in the future. Each trainee registers for the minimum of 1 and maximum of 3 courses. The number of trainees which can register for a course is not limited. Each course is assigned to maximum number of 5 instructors. A course might be assigned to no instructors, if there are no trainees registered for it. An instructor might be assigned to a maximum of 10 courses. Each course is organised in 10 sessions.
Each session is taught by one instructor, only. An instructor might be in charge of any number of sessions (obviously, an implicit constraint exists, namely that instructor can’t be in charge of more than 100 sessions, but you might disregard this constraint).