8/10/2019 CSCI235 Autumn2014 Assignments Assignment 2

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University Of Wollongong in DubaiCSCI235Databases

Assignment 2S E T 4

Date of submission:Thursday 5 pm-Week 13.

Note:

This assignment is a group work of no more than two students. Detection of plagiarism or

copying of work will lead to severe penalty.

Normalization

Objectives:

The objective of this assignment is to normalize the given conceptual database schema.

1. Consider the following collection of relations and dependencies. Assume that eachrelation is obtained through decomposition from a relation with attributes ABCDEFGHI

and that all the known dependencies over relation ABCDEFGHI are listed for each

question.

a. Identify the candidate key(s) for R

b. state the strongest normal form that the relation is in (1NF, 2NF, 3NF and BCNF)c. If it is not in BCNF, decompose it into a collection of BCNF relations that

preserves the dependencies.

d. If it is not possible to decompose it to BCNF, then decompose it to highest normalform possible.

R1(A,C,B,D,E),I. ABC, E D == A->B,A->C , E-> D (3NF) keys A, E

II. A

D, D

B, D

C, D

E == A->B, D->C,D->E (3NF) keys A, DIII. DE C, CB A == D->C,E->C,C->A,B->A (3NF) keys d,e,c,bIV. AB C, AB D, A C, B D== A->C ,B->C,A->D,B->D(3NF) keys a, b

2. Consider the attribute set R= ABCDEGH and the following FD set:F= { AB C, AC B, AD E, B D, BC A, E G}

a. Name the strongest normal form that each relation satisfies. Decompose it into a

collection of BCNF relations if it is not in BCNF.

V. ABCD == A->B,A->C.VI. DCEGH==E->G,D->E.

VII. ACEH== A->C.

b. which of the following decompositions of R=ABCDEG with the same set of

dependencies F, is a) dependency preserving b) lossless-join?

{AB, BC, ABDE, EG}

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Transaction Management:Objectives:

The objective of this assignment is to practice assigning isolation levels to control

concurrency in database transactions.

Consider the university enrollment database schema:

Student(snum: integer,sname: string, major: string, level: string, age: integer)

Class(name: string, meets at: time, room: string,fid: integer)Enrolled(snum: integer, cname: string)

Faculty(fid: integer,fname: string, deptid: integer)

The meaning of these relations is straightforward; for example, Enrolled has one record

per student-class pair such that the student is enrolled in the class.

For each of the following transactions,

a. Write the SQL command that implements themb. Write SQL SET ISOLATION LEVEL and explain why you chose it.

T1.

Create a class name: Introduction toDatabase SystemsMove all students from class Interactive Systems to Introduction toDatabase Systems

T2.

Enroll all MIS major students in the class Database Ithat meets at KV-312

T3.

Change the faculty id of all classes that their name has Databaseto fid of 110

T4.

For each class, show the number of students enrolled in the class.

T5.

For all classes with maximum students enrolled in them return the class name and number of

students

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PL/SQL

Objectives:The objective of this assignment is to practice with PL/SQL.

A. Answer the following questions based on the PL/SQL program below You are working for a company and your boss gives you the following table Employeeand a stored procedure below and a program (on next page).

A.1. Describe what the program does.The procedure takes in a the employee id and new salaryIf the id is in database and salary is not null then it updates it to new salary providedAccording to number of years of experienceOtherwise it gives an error message

A.2. Run the program (on the next page) and show the resulting table. (if you find a bug in theprogram, you need to fix them first)

Employee Table

Employee Year_Experience Salary10001 5 5000

10002 10 10000

10003 2 5000

10004 4 5000

10005 3 3000

10006 8 10000

PROCEDURE update_ES (iSSN INTEGER, fNewSalary NUMBER) IS

fCurSalary NUMBER(10, 2);

missing_salary EXCEPTION

BEGIN

SELECT Salary INTO fCurSalary FROM Employee WHERE SSN = iSSN;

IF fCurSalary IS null THEN RAISE missing_salary;

ELSE

UPDATE Employee SET Salary = fNewSalary WHERE SSN = iSSN;END IF;

COMMIT;EXCEPTION

WHEN NO_DATA_FOUND THEN INSERT INTO item_audit

VALUES (iSSN, 'Invalid Employee identifier.'); COMMIT;

WHEN missing_salary THEN INSERT INTO item_audit

VALUES (iSSN, 'Salary is null.'); COMMIT;WHEN OTHERS THEN

ROLLBACK;INSERT INTO item_audit VALUES (iSSN, 'Miscellaneous error.');COMMIT;

END update_ES;

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10001 0.05 5000 5250

10002 0.1 10000 11000

10003 0.02 5000 5100

10004 0.04 5000 5200

10005 0.03 30003090

10006 0.08 10000 10800

DECLARECURSOR emp_cursor ISSELECT emp_year_exp, emp_salary, emp_SSN FROM Employee;

emp_rec item%ROWTYPE;

BEGINFOR emp_rec IN emp_cursor LOOP

IF (emp_rec.emp_year_exp > 10)THEN

update_ES(emp_rec.emp_SSN, emp_rec.salary +emp_rec.salary * 0.10)

ELSIF ((emp_rec.emp_year_exp 5))

THENupdate_ES(emp_rec.emp_SSN, item emp_rec.salary +

emp_rec.salary * 0.05);ELSIF ((emp_rec.emp_year_exp < 5) AND

(emp_rec.emp_year_exp >= 3))THEN

;

ELSIF ((emp_rec.emp_year_exp < 3)DELETE Employee WHERE CURRENT OF emp_cursor;

END IF;

END LOOP;COMMIT; -- Commit the transaction

WHEN OTHERS THENROLLBACK;

END;