Riyadh Philanthropic Society For Science
Prince Sultan College For Woman
Dept. of Computer & Information Sciences
CS 340
Introduction to Database Systems
(Chapter 6 Tutorial)
Exercise 1
Given the Following database schema:
Specify the following queries in:
• Relation algebra
• Tuple relational calculus
• Domain relational calculus
Chapter 6 Tutorial
Only for a, b, c, f, i, j
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Exercise 1 - a
Retrieve the names of all employees in department 5 who work more
than 10 hours per week on the ‘Product x’ project.
Relational Algebra:
PROJ_X
 PNAME = ‘Product x’ (PROJECT)
EMP_WORK_10
EMP_DEPT_5
RESULT
Chapter 6 Tutorial
 HOURS>10 (PROJ_X
 DNO=5 (EMPLOYEE
PNUMBER=PNO WORKS_ON)
SSN=ESSN EMP_WORK_10)
p FNAME, LNAME (EMP_DEPT_5)
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Exercise 1 - a
Tuple relational calculus:
{e.FNAME, e.LNAME | EMPLOYEE(e) AND e.DNO=5 AND
(p) (w) (PROJECT(p) AND WORKS_ON(w) AND
p.PNAME=‘Product x’ AND w.HOURS>10 AND e.SSN=w.ESSN
AND p.PNUMBER= w.PNO)}
Domain relational calculus:
{qs | (z) (a) (b) (e) (f) (g) (EMPLOYEE(qrstuvwxyz) AND
PROJECT(abcd) AND WORKS_ON(efg) AND z=5 AND
a=‘Product x’ AND g>10 AND t=e AND b=f)}
Chapter 6 Tutorial
3
Exercise 1 - b
List the names of all employees who have a dependent with the same
first name as themselves.
Relational Algebra:
EMP
(EMPLOYEE
RESULT
Chapter 6 Tutorial
SSN=ESSN AND FNAME=DEPENDENT_NAME DEPENDENT)
p FNAME, LNAME (EMP)
4
Exercise 1 - b
Tuple relational calculus:
{e.FNAME, e.LNAME | EMPLOYEE(e) AND (d)
(DEPENDENT(d) AND e.SSN=d.ESSN AND
e.FNAME=d.DEPENDENT_NAME)}
Domain relational calculus:
{qs | (t) (a) (b) (EMPLOYEE(qrstuvwxyz) AND
DEPENDENT(abcde) AND t=a AND q=b)}
Chapter 6 Tutorial
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Exercise 1 - c
Find the names of all employees who are directly supervised by
‘Franklin Wong’.
Relational Algebra:
 FNAME=‘Franklin’ AND LNAME=‘Wong’ (EMPLOYEE)
FW_SSN
p SSN (FW)
FW_EMP
(EMPLOYEE SUPERSSN=SSN FW_SSN)
RESULT
p FNAME, LNAME (FW_EMP)
FW
Chapter 6 Tutorial
6
Exercise 1 - c
Tuple relational calculus:
{e.FNAME, e.LNAME | EMPLOYEE(e) AND (s) (EMPLOYEE(s)
AND s.FNAME=‘Franklin’ AND s.LNAME=‘Wong’ AND
e.SUPERSSN=s.SSN)}
Domain relational calculus:
{qs | (y) (a) (c) (d) (EMPLOYEE(qrstuvwxyz) AND
EMPLOYEE(abcdefghi) AND a=‘Franklin’ AND c=‘Wong’ AND
y=d)}
Chapter 6 Tutorial
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Exercise 1 - d
For each project, list the project name and the total hours per week
(by all employees) spent on that project.
Relational Algebra:
PROJ_HOURS1(PNO, T_HOURS)
PNO
SUM HOURS (WORKS_ON)
PROJ_HOURS2
(PROJ_HOURS1 PNO=PNUMBER PROJECT)
RESULT
p PNAME, T_HOURS (PROJ_HOURS2)
Chapter 6 Tutorial
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Exercise 1 - e
Retrieve the names of all employees who work on every project.
Relational Algebra:
PROJ_EMP
p PNO, ESSN (WORKS_ON)
ALL_PROJ(PNO)
p PNUMBER (PROJECT)
EMP_ALL_PROJ1
PROJ_EMP .. ALL_PROJ
EMP_ALL_PROJ2
(EMPLOYEE SSN=ESSN EMP_ALL_PROJ1)
RESULT
p FNAME, LNAME (EMP_ALL_PROJ2)
Chapter 6 Tutorial
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Exercise 1 - f
Retrieve the names of all employees who do not work on any project.
Relational Algebra:
ALL_EMP
p SSN (EMPLOYEE)
W_EMP(SSN)
p ESSN (WORKS_ON)
N_W_EMP
ALL_EMP - W_EMP
RESULT
p FNAME, LNAME (EMPLOYEE * N_W_EMP)
Chapter 6 Tutorial
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Exercise 1 - f
Tuple relational calculus:
{e.FNAME, e.LNAME | EMPLOYEE(e) AND NOT(w)
(WORKS_ON(w) AND e.SSN=w.ESSN)}
Domain relational calculus:
{qs | (t) (EMPLOYEE(qrstuvwxyz) AND NOT(a)
(WORKS_ON(abc) AND t=a))}
Chapter 6 Tutorial
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Exercise 1 - g
For each department, retrieve the department name and the average
salary of all employees working in that department.
Relational Algebra:
D_AVG_S(DNUMBER, AVG)
RESULT
Chapter 6 Tutorial
DNO
AVERAGE SALARY (EMPLOYEE)
p DNAME, AVG (D_AVG_S * DEPARTMENT)
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Exercise 1 - h
Retrieve the average salary of all female employees.
Relational Algebra:
 SEX=‘F’ (EMPLOYEE)
RESULT(AVG_F_S)
AVERAGE SALARY (F_EMP)
F_EMP
Chapter 6 Tutorial
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Exercise 1 - i
Find the names and addresses of all employees who work on at least
one project located in Houston but whose department has no location
in Houston.
Relational Algebra:
H_PROJ
 PLOCATION=‘Houston’ (PROJECT)
E_H_PROJ(SSN)
p ESSN (WORKS_ON PNO=PNUMBER H_PROJ)
H_DEPT
p DNUMBER ( DLOCATION=‘Houston’ (DEPT_LOCATION))
ALL_DEPT
p DNUMBER (DEPARTMENT)
N_H_DEPT
ALL_DEPT - H_DEPT
E_N_H_DEPT
p SSN (EMPLOYEE DNO=DNUMBER N_H_DEPT)
EMP
E_H_PROJ
E_N_H_DEPT
RESULT
p FNAME, LNAME, ADDRESS (EMPLOYEE * EMP)
Chapter 6 Tutorial
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Exercise 1 - i
Tuple relational calculus:
{e.FNAME, e.LNAME, e.ADDRESS | EMPLOYEE(e) AND (p)
(w) (PROJECT(p) AND WORKS_ON(W) AND
p.PLOCATION=‘Houston’ AND e.SSN=w.ESSN AND
w.PNO=p.PNUMBER AND NOT(l) (DEPT_LOCATION(l) AND
l.DLOCATION=‘Houston’ AND e.DNO=l.DNUMBER))}
Domain relational calculus:
{qsv | (t) (z) (EMPLOYEE(qrstuvwxyz) AND (b) (c) (e) (f)
(PROJECT(abcd) AND WORKS_ON(efg) AND c=‘Houston’ AND
t=e AND b=f AND NOT(h) NOT(i) (DEPT_LOCATIONS(hi)
AND i=’Houston’ AND z=h))}
Chapter 6 Tutorial
15
Exercise 1 - j
List the last names of all department managers who have no
dependents.
Relational Algebra:
D_MGR(SSN)
p MGRSSN (DEPARTMENT)
E_W_DEPENDENT(SSN)
p ESSN (DEPENDENT)
EMP
D_MGR - E_W_DEPENDENT
RESULT
p LNAME (EMPLOYEE * EMP)
Chapter 6 Tutorial
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Exercise 1 - j
Tuple relational calculus:
{e.LNAME | EMPLOYEE(e) AND (d) (DEPARTMENT(d) AND
e.SSN=d.MGRSSN AND NOT(x) (DEPENDENT(x) AND
e.SSN=x.ESSN))}
Domain relational calculus:
{s | (t) (EMPLOYEE(qrstuvwxyz) AND (c)
(DEPARTMENT(abcd) AND t=c AND NOT(e)
(DEPENDENT(efghi) AND t=e))}
Chapter 6 Tutorial
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