Chapter 7: Problem 34
What problems arise if one makes the supervises relationship mandatory for either the supervising employee or the employee who is supervised?
Chapter 7: Problem 34
What problems arise if one makes the supervises relationship mandatory for either the supervising employee or the employee who is supervised?
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Get started for freeIn some large organizations where there are several buildings and floors we see room numbers that encode information about the building, floor, and room number. For example in case the room 3C13 stands for room 13 on the third floor of the Centennial building. Suppose we need to include Room in an ERD. How would you represent the room number given that you must include atomic attributes only?
Consider a marriage entity type and attributes marriage date, marriage location, husband, wife. Each marriage will only have one value for each of these attributes. Illustrate the marriage entity and its single-valued attributes in an ERD .
A college or university will keep track of several addresses for a student, but each of these can be named differently: for example, consider that a student has a mailing address and a home address. Create an ERD for a student entity type with two composite attributes for student addresses where each comprises several single-valued attributes.
Consider a library and the fact that books are loaned out to library members. Dates could be used heavily for the date a book was borrowed, the date the book was returned, and the due date for a book. Consider an entity type Loan that has attributes book identifier, member identifier, date borrowed, date due, date returned. What combination of attributes would be a key? Which attributes are key attributes? Which attributes are non-key attributes?
Consider an educational environment where the institution tracks the performance of each student. Often this is called the students overall average, or overall grade point average. Is such an attribute a derived attribute? How is its value determined?
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