Database Reference
In-Depth Information
The Student acceptance Letter
Figure 5-50 shows the acceptance letter that Highline sends to its incoming students. The data
items in this letter that need to be represented in the data model are shown in boldface. In
addition to data concerning the student, this letter also contains data regarding the student's
major department as well as data about the student's adviser.
We can use this letter to add an Advises/Advised By relationship to the data model.
However, which entity should be the parent of this relationship? Because an adviser is a pro-
fessor, it is tempting to make PROFESSOR the parent. However, a professor acts as an adviser
within the context of a particular department. Therefore, Figure 5-51 shows APPOINTMENT
as the parent of STUDENT. To produce the report in Figure 5-50, the professor's data can be
retrieved by accessing the related APPOINTMENT entity and then accessing that entity's
PROFESSOR parent. This decision is not cut and dried, however. One can make a strong argu-
ment that the parent of the relationship should be PROFESSOR.
According to this data model, a student has at most one adviser. Also, a student must
have an adviser, but no professor (via APPOINTMENT) need advise any students. These
constraints cannot be determined from any of the reports shown and will need to be veri-
fied with the users. The acceptance letter uses the title Mr . in the salutation. Therefore, a
new attribute called Title is added to STUDENT. Observe that this Title is different from
the one in APPOINTMENT. This difference will need to be documented in the data model
to avoid confusion. The acceptance letter also shows the need to add new home address
attributes to STUDENT.
The acceptance letter reveals a problem. The name of the student is Fred Parks, but
we have allocated only one attribute, StudentName, in STUDENT. It is difficult to reliably
disentangle first and last names from a single attribute, so a better model is to have two
attributes: StudentFirstName and StudentLastName. Similarly, note that the adviser in this
letter is Elizabeth Johnson. So far, all professor names have been in the format Johnson,
Elizabeth. To accommodate both forms of name, ProfessorName in PROFESSOR must
be changed to the two attributes ProfessorFirstName and ProfessorLastName. A similar
change is necessary for DeanName. These changes are shown in Figure 5-52, which is the
final form of this data model.
Figure 5-50
Highline University Sample
Student Acceptance Letter
Mr. Fred Parks
123 Elm Street
Los Angeles , CA 98002
Dear Mr . Parks :
You have been admitted as a major in the Accounting Department at Highline
University, starting in the Fall Semester, 2011. The office of the Accounting
Department is located in the Business Building, Room 210 .
Your adviser is professor Elizabeth Johnson , whose telephone number is 232 -
8740 and whose office is located in the Business Building, Room 227 . Please
schedule an appointment with your adviser as soon as you arrive on campus.
Congratulations and welcome to Highline University!
Sincerely,
Jan P. Smathers
President
JPS/rkp
 
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