1. Exercise 2 Relational Calculus
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2. 6 Relations of Company
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3. FNAME,LNAME(SALARY>‘50000’ (EMPLOYEES))
Find the first and last names of all employees whose salary is above $50,000
Rel Algebra 
FNAME,LNAME(SALARY>‘50000’ (EMPLOYEES))
Tuple Rel Calculus 
{t.FNAME,t.LNAME|EMPLOYEE(x) AND t.SALARY>‘50000’))
Domain Rel Calculus 
{ac|(Ǝi) EMPLOYEE(abcdefghijkl) AND i>‘50000’))
SQL 
select FNAME, LNAME
from EMPLOYEES
where SALARY>‘50000’
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4. Exercises
(a) Retrieve the names of employees in department 5 who work more than 10 hours per week on the 'ProductX' project.
(b) List the names of employees who have a dependent with the same first name as themselves.
(c) Find the names of employees that are directly supervised by 'Franklin Wong'. 
(e) Retrieve the names of employees who work on every project.
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5. Exercises
(f) Retrieve the names of employees who do not work on any project.
(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.
(j)List the last names of department managers who have no dependents.
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6. P W E WORKS_ON_ProductX (Rel.A)
Retrieve the names of employees in department 5 who work more than 10 hours per week on the 'ProductX' project
Graphical approach can be used to help the logical and prosedural approach
Example of above query, the graphical approach: clue from query the relations that (may) work on the query are in the red text P
Pnumber=Pno W
ESSN=SSN E
Fname, Lname (?)
Pname=‘ProductX’
Hours > 10
Dno = 5
ProductX
> 10 5
WORKS_ON_ProductX (Rel.A)
(PNAME=‘ProductX’(PROJECT) PNUMBER=PNO(WORKS_ON))
EMPLOYEE_DEPT5_WORKS_MORE_10_onProductX (Rel.B)
((EMPLOYEE) SSN=ESSN( HOURS>10(Rel.A)))
RESULT  FNAME,LNAME(DNO=‘5’ (Rel.B))
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7. P W E { e.LNAME, e.FNAME | EMPLOYEE(e) AND e.DNO=5 AND (Ǝp)(Ǝw)
Retrieve the names of employees in department 5 who work more than 10 hours per week on the 'ProductX' project P
Pnumber=Pno W
ESSN=SSN E
Fname, Lname (?)
Pname=‘ProductX’
Hours > 10
Dno = 5
ProductX
> 10 5
{ e.LNAME, e.FNAME | EMPLOYEE(e) AND e.DNO=5 AND (Ǝp)(Ǝw)
(WORKS_ON(w) AND PROJECT(p) AND e.SSN=w.ESSN AND
w.PNO=p.PNUMBER AND p.PNAME='ProductX' AND w.HOURS>10 ) }
{ qs | EMPLOYEE(qrstuvwxyz) AND z=5 AND (Ǝa) (Ǝb) (Ǝe)
(Ǝf) (Ǝg) ( WORKS_ON(efg) AND PROJECT(abcd)
AND t=e AND f=b AND a='ProductX' AND g>10 ) }
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8. List the names of employees who have a dependent with the same first name as themselves.Dp
Depend_name=Fname E
Fname, Lname (?)
ESSN=SSN
RESULT  FNAME,LNAME(DEPENDENT
(ESSN,DEPEND_NAME)=(SSN,FNAME)(EMPLOYEE))
{ e.LNAME, e.FNAME | EMPLOYEE(e) AND (Ǝd) ( DEPENDENT(d)
AND e.SSN=d.ESSN AND e.FNAME=d.DEPENDENT_NAME ) }
{ qs | (Ǝt) (Ǝa) (Ǝb) ( EMPLOYEE(qrstuvwxyz) AND
DEPENDENT(abcde) AND a=t AND b=q ) }
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9. Find the names of employees that are directly supervised by 'Franklin Wong'.
E_SSN_FRANKLIN_WONG(Rel.A)
( SSN( FNAME=‘FRANKLIN’ LNAME=‘WONG’(EMPLOYEE)))
E_SUPERVISED_BY_FRANKLIN_WONG (Result)
( FNAME, LNAMES(EMPLOYEE) SUPERSSN=SSN(Rel.A))
{ e.LNAME, e.FNAME | EMPLOYEE(e) AND (Ǝs) ( EMPLOYEE(s) AND
s.FNAME='Franklin' AND s.LNAME='Wong' AND e.SUPERSSN=s.SSN ) }
{ qs | (Ǝy) (Ǝa) (Ǝc) (Ǝd) ( EMPLOYEE(qrstuvwxyz)
AND EMPLOYEE(abcdefghij) AND a='Franklin' AND c='Wong' AND y=d ) }
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10. Retrieve the names of employees who work on every project
ALL_EMPLOYEE(SSN, PNO)(Rel.A) ( SSN, PNO(WORKS_ON))
ALL_PROJECT(PNO)(Rel.B) ( PNO(PROJECT))
E_ALL_PROJECT ( Rel.A÷Rel.B)
RESULT ( FNAME, LNAME (E_ALL_PROJECT * EMPLOYEE))
{ e.LNAME, e.FNAME | EMPLOYEE(e) AND (Ѵp) ( NOT(PROJECT(p))
OR (Ǝw) (WORKS_ON(w) AND p.PNUMBER=w.PNO AND w.ESSN=e.SSN ) ) }
{ qs | (Ǝt) ( EMPLOYEE(qrstuvwxyz) AND (Ѵb) (
NOT(PROJECT(abcd)) OR (Ǝe) (Ǝf) (WORKS_ON(efg) AND e=t AND f=b) ) }
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11. Retrieve the names of employees who do not work on any project
ALL_EMPLOYEE(SSN)(Rel.A) ( SSN(EMPLOYEE))
ALL_EMPLOYEE_WORKING(SSN)(Rel.B) ( ESSN(WORKS_ON))
E_NOT_WORKING ( Rel.A - Rel.B)
RESULT ( FNAME, LNAME (
(EMPLOYEE) SSN=ESSN(E_NOT_WORKING))
{ e.LNAME, e.FNAME | EMPLOYEE(e) AND NOT(Ǝw) ( WORKS_ON(w)
AND w.ESSN=e.SSN ) }
{ qs | (Ǝt) ( EMPLOYEE(qrstuvwxyz) AND NOT(Ǝa)
(WORKS_ON(abc) AND a=t ))}
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12. { e.LNAME, e.FNAME, e.ADDRESS | EMPLOYEE(e) AND (Ǝp) (Ǝw)
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
{ e.LNAME, e.FNAME, e.ADDRESS | EMPLOYEE(e) AND (Ǝp) (Ǝw)
(WORKS_ON(w) AND PROJECT(p) AND e.SSN=w.ESSN AND
w.PNO=p.PNUMBER AND p.PLOCATION='Houston'
AND NOT(Ǝl) ( DEPT_LOCATIONS(l) AND
e.DNO=l.DNUMBER AND l.DLOCATION='Houston' ) ) }
{ qsv | (Ǝt) (Ǝz) ( EMPLOYEE(qrstuvwxyz) AND (Ǝb)
(Ǝc) (Ǝe) (Ǝf) ( WORKS_ON(efg)
AND PROJECT(abcd) AND t=e AND f=b AND c='Houston' AND
NOT(Ǝh) NOT(Ǝi) ( DEPT_LOCATIONS(hi)
AND z=h AND i='Houston’ ) ) }
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13. List the last names of department managers who have no dependents
D_MNG_SSN(Rel.A)( SSN(DEPARTMENT)
E_WITH_DEPENDENT(Rel.A)( SSN(DPENDENT)
MNGR_NO_DEPENDENT(Rel.A – Rel.B)
RESULT( LNAME(EMPLOYEE * MNGR_NO_DEPENDENT))
{ e.LNAME | EMPLOYEE(e) AND (Ǝd) ( DEPARTMENT(d) AND
e.SSN=d.MGRSSN AND
NOT(Ǝx) (DEPENDENT(x) AND e.SSN=x.ESSN) ) }
{ s | (Ǝt) ( EMPLOYEE(qrstuvwxyz) AND (Ǝc) ( DEPARTMENT(abcd)
AND t=c AND NOT(Ǝe) (DEPENDENT(efghi) AND e=t) ) }
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