Database Management System a What are the 2 valid reasons to

Database Management System:

a. What are the 2 valid reasons to form subsets in an EER diagram?

b. What is a defining predicate and where is it placed on an EER diagram?

Solution

more advantageous-ER (EER) version concepts<br/> The EER version introduce the extra ideas of subclasses, superclasses, specialization generalization, characteristic inheritance. The ensuing model is called the improved-ER or prolonged ER version. it\'s miles used to model programs greater absolutely and accurately if wanted. It consists of some item-oriented ideas, which includes inheritance .<br/>14<br/>
2. Subclasses and Superclasses<br/><ul><li>An entity type may additionally have additional meaningful subgroupings of its entities
3. example: worker may be in addition grouped into SECRETARY, ENGINEER, supervisor, TECHNICIAN, SALARIED_EMPLOYEE, HOURLY_EMPLOYEE,…
4. every of these groupings is a subset of employee entities
5. each is known as a subclass of worker