Solution of 7.18
The following symbols are used:

for
SELECT

for
PROJECT

for
EQUI-JOIN
*
for
NATURAL JOIN
f
for
FUNCTION
-:for
DIVISION
for
SET DIFFERENCE
(a) Retrieve the names of employees in department 5 who work more than 10 hours per week on
the 'ProductX' project.
R1  ( PNAME = 'ProductX' (PROJECT))
R2  (R1)  PNUMBER = PNO (WORKS_ON)
R3  (EMPLOYEE) * SSN=ESSN ( HOURS>10 (R2))
Result   FNAME, LNAME ( DNO=5 (R3))
Result
FNAME
John
Joyce
LNAME
Smith
English
(b) List the names of employees who have a dependent with the same first name as themselves.
R1  (EMPLOYEE)  (SSN=ESSN) AND (ESSN=DEPENDENT_NAME) (DEPENDENT)
Result   FNAME, LNAME (R1)
Result (empty)
FNAME
LNAME
(c) Find the names of employees that are directly supervised by 'Franklin Wong'
R1   SSN ( FNAME = 'Frankin' AND LNAME = 'Wong' (EMPLOYEE))
R2  (EMPLOYEE) SUPERSSN = SSN (R1)
Result   FNAME, LNAME (R2)
Result
FNAME
John
Ramesh
Joyce
LNAME
Smith
Narayan
English
1
(d) For each project, list the project name and the total hours per week (by all employees) spent on
that project.
R1(PNO,TOT_HRS)  PNO f SUM HOURS (WORKS_ON)
Result   PNAME, TOT_HRS ((R1)  PNO= PNUMBER (PROJECT))
Result
PNAME
ProductX
ProductY
ProductZ
Computerization
Reorganization
NewBenefits
TOT_HRS
52.5
37.5
50.0
55.0
25.0
55.0
(e) Retrieve the names of employees who work on every project.
R1 (PNO, SSN)   PNO, ESSN (WORKS_ON)
R2 (PNO)   PNUMBER (PROJECT)
R3   FNAME, LNAME (R1 -:- R2)
Result   FNAME, LNAME (EMPLOYEE * R3)
Result (empty)
FNAME
LNAME
(f) Retrieve the names of employees who do not work on any project.
R1   SSN (EMPLOYEE)
R2 (SSN)   ESSN (WORKS_ON)
R3  R1 - R2
Result   FNAME, LNAME (EMPLOYEE * R3)
Result (empty)
FNAME
LNAME
(g) For each department, retrieve the department name, and the average salary of employees
working in that department.
R1(DNUMBER, AVG_SAL)  DNO f AVG SALARY (EMPLOYEE)
Result   DNUMBER, AVG_SAL (R1 * DEPARTMENT)
2
Result
DNUMBER
Research
Administration
Headquarters
AVG_SAL
33250
31000
55000
(h) Retrieve the average salary of all female employees.
Result (AVG_F_SAL)  f AVG SALARY ( SEX = 'F" (EMPLOYEE))
Result
AVG_F_SAL
31000
(i) Find the names and addresses of employees who work on at least one project located in
Houston but whose department has no location in Houston.
R1(SSN)   ESSN ((WORKS_ON)  PNO = PNUMBER ( PLOCATION = 'Houston' (PROJECT))))
R2   DNUMBER (DEPARTMENT) -  DNUMBER ( PLOCATION = 'Houston' (DEPARTMENT))
R3   SSN ((EMPLOYEE)  PNO = DNUMBER (R2))
R4  R1- R3
Result   FNAME, LNAME, ADDRESS (EMPLOYEE * R2)
Result
FNAME
Jennifer
LNAME
Wallace
ADDRESS
291 Berry, Bellaire, TX
(j) List the last names of department managers who have no dependents.
R1 (SSN)   MGRSSN (DEPARTMENT)
R2 (SSN)   ESSN (DEPENDANT)
R3  R1 - R2
Result   FNAME, LNAME (EMPLOYEE * E3)
Result
FNAME
James
LNAME
Borg
3
Solution of 7.27
a.
PQRABC
10 a 5 10 b 6
10 a 5 10 b 5
25 a 6 25 c 3
b.
PQRABC
15 b 8 10 b 6
15 b 8 10 b 5
c.
PQRABC
10 a 5 10 b 6
10 a 5 10 b 5
15 b 8 null null null
25 a 6 25 c 3
d.
PQRABC
15 b 8 10 b 6
Null null null 25 c 3
15 b 8 10 b 5
e.
PQR
10 a 5
15 b 8
25 a 6
10 b 6
25 c 3
10 b 5
f.
PQRABC
10 a 5 10 b 5
4