Podcast
Questions and Answers
What is the 'supervises' relationship between employees modeling?
What is the 'supervises' relationship between employees modeling?
It models the same entity set (employee) participating in the relationship set 'supervises' twice, once as the supervisor and once as the supervised employee.
What are the labels 'course_id' and 'prereq_id' called?
What are the labels 'course_id' and 'prereq_id' called?
They are called roles.
How is the situation where one course is a prerequisite for another course depicted in the relationship set 'prereq'?
How is the situation where one course is a prerequisite for another course depicted in the relationship set 'prereq'?
It is modeled by ordered pairs of course entities, where the first course takes the role of courseC1 and the second takes the role of prerequisite course C2.
What is the purpose of a top-down design process in entity-relationship modeling?
What is the purpose of a top-down design process in entity-relationship modeling?
How is specialization depicted in an entity-relationship model?
How is specialization depicted in an entity-relationship model?
What is attribute inheritance in the context of entity-relationship modeling?
What is attribute inheritance in the context of entity-relationship modeling?
What does the completeness constraint specify in the context of entity sets?
What does the completeness constraint specify in the context of entity sets?
How is total generalization specified in an ER diagram?
How is total generalization specified in an ER diagram?
What is the default type of generalization in the context of completeness constraint?
What is the default type of generalization in the context of completeness constraint?
What does it mean when the completeness constraint for a generalized higher-level entity set is total?
What does it mean when the completeness constraint for a generalized higher-level entity set is total?
