Bài tập cơ sở dữ liệu nâng cao tuần 1

The university keeps track of each student's name, student number, social security number, current address and phone, permanent address and phone, birth date, sex, class freshman, sophom

CSC380 – Fundamentals of Database Systems

Tutorial # 3

7.16 Consider the following set of requirements for a UNIVERSITY database that is used to keep track of students' transcripts This is similar but not identical to the database shown

in Figure 1.2:

a The university keeps track of each student's name, student number, social security number, current address and phone, permanent address and phone, birth date, sex, class (freshman, sophomore, , graduate), major department, minor department (if any), and degree program (B.A., B.S., , Ph.D.) Some user applications need

to refer to the city, state, and zip of the student's permanent address, and to the student's last name Both social security number and student number have unique values for each student

b Each department is described by a name, department code, office number, office phone, and college Both name and code have unique values for each department

c Each course has a course name, description, course number, number of semester hours, level, and offering department The value of course number is unique for each course

d Each section has an instructor, semester, year, course, and section number The section number distinguishes different sections of the same course that are taught during the same semester/year; its values are 1, 2, 3, , up to the number of sections taught during each semester

e A grade report has a student, section, letter grade, and numeric grade (0, 1, 2, 3, 4 for F, D, C, B, A, respectively)

Design an ER schema for this application, and draw an ER diagram for that schema Specify key attributes of each entity type and structural constraints on each relationship type Note any unspecified requirements, and make appropriate assumptions

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Assumptions:

• Every department must have at least one student enrolled in it as a major

• A student must specify his major when he/she joins the university

• Not all departments are used as a minor department for a student’s degree

• Every department must offer at least one course

• Every course must belong to exactly one department

• Not all courses will have sections (a course may be new and will not

be offered until next year, or there is no instructor available to teach the course)

• A section may not have any students enrolled in it

• A student may not sign up for any classes (sections) (for example, the student dropped that semester for medical reasons

7.17 Composite and multi-valued attributes can be nested to any

STUDENT entity type to keep track ofprevious college education Such an attribute will have one entry for each collegepreviously attended, and this entry is composed of: college name, start and enddates, degree entries (degrees awarded at that college, if any), and transcriptentries (courses completed at that college,

if any) Each degree entry is formed ofdegree name and the

month and year it was awarded, and each transcript entry

isformed of a course name, semester, year, and grade Design an attribute to holdthis information Use the conventions of

Figure 7.5.

Answer:

{ PreviousEducation ( CollegeName,

StartDate,

EndDate,

{ Degree (DegreeName, Month, Year) },

{ Transcript (CourseName, Semester, Year, Grade) }

)

}

• Note (background information, not essential for

examination):

• Note that in Computer Science we usually denote such nested

structures in the BNF notationfor defining

grammars:PreviousEducationList::

PreviousEducation*PreviousEducation: CollegeName StartDate

EndDate Degree* Transcript*Degree : DegreeName Month

YearTranscript : CourseName Semester Year Grade

•

• Selected exercises Chapter 3, Elmasri & Navathe

Problem 7.19

Consider the ER diagram in Figure 7.20, which shows a simplified schema for an airline reservation system Extract from the ER diagram the requirements and constraints that produced this schema Try to be as precise as possible in your requirements and constraints specification.

Airport

- Each airport must have a unique airport code

- Each airport must have a name

- Each airport must have the city listed for which it is located

- Each airport must have the state listed for which it is located

Airplane

- Each airplane can arrive at an airport during a flight leg

- Every airplane has a unique airplane id number

- Every airplane has a maximum capacity (Seats)

Flight

- Each flight has a unique flight number

- A flight is composed of one or more flight legs

- Each flight must have a designated airline

- Each flight leg must have a departure and arrival time defined

Fare

- Each fare must have a unique code (First class)

- Each fare must have a cost/price

- Each fare may have restrictions

Seat

- Each seat has a unique seat number (Seat 14C)

- Each seat is based on a customer reservation

- Seats are allocated to specific flight legs

- The number of seats per flight leg cannot exceed the airplane's

maximum capacity

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