mapping ER
Posted by: mayada rida
Date: August 11, 2006 06:01PM

Dear All,

I am trying to map my logical data model into physical tables implementation. The problem i have is that i have supertype/subtype entities and not sure how to deal with them.

Basically i am developing a booking system for conference rooms at a university. if a lecturer books a room, they don't have to pay anything, whilst students have to pay for booking.

My LDM, has the following entities: USER (Supertype), student and lecturer subtypes. The student entity has 1:m relationship to a student_course entity which in turn has a 1:m relationship with conf_room_booking entity. the student course decides how much the student pays for the booking.

the lecturer entity is linked directly to conf_room_booking with 1:m relationship.

I am not sure how to phyisically implement this. I could divide the conf_room_booking entity into sub entities (one for student and one for lecturer) but this will make application development complex, since bookings will be in 2 seperate tables, also duplicate bookings may happen which i do not want. at the same time, booking for student should have a cost but the lecturer can book free of charge.

I hope someone can help.

Regards

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mapping ER
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