It include the topic Relational algebra, which is very useful for the beginners.

4. •Two formal language for the relational model

5. • Basic set of operation for the relational model.
• These operation enable a user to specify basic retrieval requests.
• The result of a retrieval is a new relation, which can be further
manipulated using operations of same algebra.
•it is important for several reasons:
 provides formal foundation for relational
model
 used as basis for implementing and
optimizing queries in RDMS

6. No commercial RDBMS in use today
provides an interface for the relational
queries.
•Relational algebra operations can be divided into
UNION
INTERSECTION
SET DIFFERENCE
CARTESIAN PRODUCT
SELECT
PROJECT
JOIN etc.

7. :Operate on a single relation

8. It select certain rows
Syntax :
<selection condition>
(R)
<selection condition> is made up of number of clauses of the form
<attribute name > <comparison op> <attribute name>
OR
<attribute name > <comparison op> <constant value>
{ =,<,>,<=,>=,!= }

9. Lets try. . .
Ex :
(DNO=4 )
(EMPLOYEE)
Ex :
(SALARY>25000)
(EMPLOYEE)

10. Clauses can be connected by the
Boolean operators and, or ,not to from a
general selection condition.
(DNO=4 AND SALARY>25000) OR (DNO=5 AND SALARY>30000)
Answer?????
(EMPLOYEE)

11. SELECT operation is commutative :
<cond1>
(
<cond2>
(R)) =
<cond2>
(
<cond1>
Cascade of SELECT operation:
<cond1>
(
<cond2>
(… (
<condn>
(R)). . . ))
=
(
<cond1> AND <cond2> AND . . . AND <condn>
(R)
(R))

12. It select certain columns
Syntax :
<attribute list >
(R)
Duplicate elimination : it removes any duplicate
tuples , and we get a valid relation .

13. What is the
resultant table ???
•
•
SEX, SALARY(EMPLOYEE)
,Lname,Fname,SALARY(EMPLOYEE)

14. Duplicate
elimination
I WANT ANSWERS. .
NOT QUESTIONS.
FNAME, LNAME, SALARY( DNO=5(EMPLOYEE))

16. We can write the operations as a single algebra
expression by nesting the operation
or
we can apply one operation at a time and create
intermediate result relations.
FNAME, LNAME, SALARY( DNO=5(EMPLOYEE))
Can replace with
DEPCS2 
RESULT 
DNO=5(EMPLOYEE)
FNAME, LNAME, SALARY
(DEPCS2)

17. Renaming of attribute
TEMP  DNO=5(EMPLOYEE)
R(FIRSTNAME,LASTNAME,SALARY)
FNAME, LNAME, SALARY
(TEMP)

18. A formal RENAME (rho) operations:
• rename either relation name, attribute name or both
s (R)
(B1,B2,…Bn)
S: new table name;
Bn: new attribute name
(R)
s(B1,B2,…Bn)
(R)

19. :R S
: Include all tuples
:Duplicates are eliminated
:R S
: include all tuples that are in both R & S
:R S
: include all tuples that are in R but not in S

20. Example:
Union compatible
• same degree
• corresponding pair have same number

21. Q. Retrieve the social security Number of
all employees who either work in
department 5 or directly supervise an
employee who works department 5.

22. •UNION and INTERSECTION are
commutative but SET
DIFFERENCE is not.
R
S =R
S – (R-S )-(S-R)

25. • Also known as CROSS PRODUCT or CROSS JOIN
• Denoted by X
• syntax :
• tab1 X tab2
• also binary set operations.
• if A has m tuples and B has n tuples then A X B has m * n
tuples .
• Cartesian product followed by SELECT is used to identify
and select related tuples from two relation.

26. EMP_ID
DESIGNATION
SALARY
101
PROFESSOR
1.25000
102
ASSOCIATE PROF
90000
103
ASSISTANT PROF
40000
TAB1
E_ID
F_NAME
M_NA
ME
L_NAME
AGE
102
SURESH
KUMAR
S
43
103
SUMI
M
MOL
23
101
SHREELEKSHMI
R
S
40
FIND salary ,name AND designation OF EACH EMPLOYEE?????

27. DESIGNATION
SALAR
Y
EMP_ID
E_ID
F_NAME
M_NAME L_NAME
AGE
PROFESSOR
1.2500
0
101
102
SURESH
KUMAR
S
43
PROFESSOR
1.2500
0
101
103
SUMI
M
MOL
23
PROFESSOR
1.2500
0
101
101
SHREELEK R
SHMI
S
40
ASSOCIATE
PROF
90000
102
102
SURESH
KUMAR
S
43
ASSOCIATE
PROF
90000
102
103
SUMI
M
MOL
23
ASSOCIATE
PROF
90000
102
101
SHREELEK R
SHMI
S
40
ASSISTANT
PROF
40000
103
102
SURESH
KUMAR
S
43
ASSISTANT
PROF
40000
103
103
SUMI
M
MOL
23
ASSISTANT
PROF
40000
103
101
SHREELEK R
SHMI
S
40

28. DESIGNATI SALARY
ON
EMP_ID
E_ID
F_NAME
PROFESSO
R
101
101
SHREELEK R
SHMI
S
40
ASSOCIATE 90000
PROF
102
102
ANIL
S
GANESH
28
ASSISTANT
PROF
103
103
SUMI
M
MOL
23
1.25000
40000
M_NAME L_NAME
AGE
SALARY
F_NAME
M_NAME
L_NAME
DESIGNATION
1.25000
RAMESH
R
VINOD
PROFESSOR
90000
ANIL
S
GANESH
ASSOCIATE PROF
40000
SUNIL
A
NARAYAN
ASSISTANT PROF

29. Write relational algebra expression
Retrieve a list of names of each
employee’s dependents.

31. • Combine related tuples from two relation into single
tuples.
• denoted by
•R
<JOIN CONDITION> S .
• Consider previous example
RESULT EMPLOYEE X DEPENDENT
FINAL  SSN= ESSN (RESULT)
The above can be replaced with
FINAL
EMPLOYEE
SSN=ESSN
DEPENDENT .

32. Retrieve the name of manager of
each department

34. •A
general join condition is of the form
<condition>AND<condition>AND. . . AND <condition>
Each condition of the form
Ai
ᶱ
Bi
Comparison operator {=,!=,<,>,<=,>=}
•A JOIN operation with such a
general join condition is
called a THETA JOIN

36. • The JOIN where the only comparison operator
used is ‘ = ‘
• It requires that two JOIN attributes have the same
name in both relation .
• if this is not the case then renaming operation done
first.
• This is basically an EQUIJOIN followed by removal of
unnecessary attributes
•Ex: DEPT_LOCS DEPARTMENT * DEPT_LOCATIONS.

37. Join attribute

38. •A JOIN operation used to combine
data from multiple relations so that
related information can be presented
in a single table. This operations are
also known as inner joins.

39. •Denoted by

40. R S

41. YEAR
TOUR_PART_EM_ID
2003
1001
2004
1001
2013
1001
2008
1004
2009
1003
2008
1003
2004
1004
2011
1004
2003
1004
2003
1002
EMP_id
NAME
ADDRESS
2004
1002
1001
SURESH
AAAA
2011
1002
1002
LALAN
BBBB
2013
1002
1003
JC
CCCC
2012
1002
1004
ANVAR
DDDD
Retrieve the name &
address of employees who
participated in all tour that
‘Suresh ‘sir attended .

42. Retrieve the names of employees who work on all
the project that ‘John Smith’ works on

45. • allowing functions of attributes to be
included in the projection
•EX:
• SALARY-DEDUCTION, SALARY * 0.25( DNO=5(EMPLOYEE))

46. • SUM
•AVERAGE
•MAXIMUM
•MINIMUM
•COUNT
Calligraphic G
•Aggregate function operation using the symbol
<grouping attribute>
<function list>
(R)

47. R(DNO,NO_OF_EMPLOYEES,AVERAGE_SAL)
COUNT ssn, AVERAGE salary(EMPLOYEE))
(EMPLOYEE)
COUNT ssn, AVERAGE salary(EMPLOYEE)
b. Dno
c.
(Dno
COUNT ssn, AVERAGE salary

48. • Used when we want to keep all the tuples in R
• three main variation are
• LEFT OUTER JOIN
• RIGHT OUTER JOIN
• FULL OUTER JOIN

49. • Relation instructor1
name
ID
Sreejith
Suresh
Sreeja
10101
12121
15151
dept_name
Comp. Sci.
Applied
PED
• Relation teaches1
ID
10101
12121
76766
course_id
CS-101
APL-101
BIO-101

50. • Join
instructor
ID
10101
12121
teaches
name
Sreejith
Suresh
dept_name
Comp. Sci.
Applied
course_id
CS-101
APL-201

51. name
ID
10101
12121
15151
Sreejith
Suresh
Sreeja
dept_name
Comp. Sci.
Applied
PED
ID
10101
12121
76766
CS-101
APL-101
BIO-101
 Left Outer Join
instructor
ID
10101
12121
15151
teaches
name
Sreejith
Suresh
Sreeja
course_id
dept_name
course_id
Comp. Sci.
Applied
PED
CS-101
APL-201
null

52. name
ID
10101
12121
15151
Sreejith
Suresh
Sreeja
dept_name
Comp. Sci.
Applied
PED
ID
10101
12121
76766
course_id
CS-101
APL-101
BIO-101
 Right Outer Join
instructor
teaches
ID
10101
12121
76766
name
Sreejith
Suresh
null
dept_name
course_id
Comp. Sci.
Applied
null
CS-101
APL-201
BIO-101

53. name
ID
dept_name
Sreejith
Suresh
Sreeja
10101
12121
15151
Comp. Sci.
Applied
PED
ID
10101
12121
76766
CS-101
APL-101
BIO-101
 Full Outer Join
instructor
teaches
ID
10101
12121
15151
76766
name
Sreejith
Suresh
Sreeja
null
course_id
dept_name
course_id
Comp. Sci.
Applied
PED
null
CS-101
APL-201
null
BIO-101

54. Additional
• semi join
• left semi join.
• Right semi join:
Rno
Name
AGE
R_no
Phone
1
Mahati
40
1
9865321245
2
Manjusha
42
3
9764316598
3
Meenu
38
5
9598946532

55. Rno
Name
AGE
1
Mahati
40
3
Meenu
38
•left semi join.
• Right semi join:
R_no
Phone
1
9865321245
3
9764316598