1. Normalization Refine data To attain a good DB design
To reduce redundancy
Minimize storage space req
Eliminate data anomalies

2. Non loss decomposition vs lossy decomposition
Un normalized table

3. Functional dependency
AB
DETERMINANT
DETERMINED
1-a a a a
1-b a b a

4. 1NF Identify and remove repeating groups
Identify and remove non atomic attr
Identify the keys for the table

5. First (sid, status,city,pid,qty)
LPU
First (sid, status,city,pid,qty)
Sid
Status
City
Pid
Qty s1 20
Jal p1
100 P2
150 s2 10
Asr P1
200
250 s3
300 s4 P3
jal p4

6. 2NF A relation is in 2NF iff It is in 1NF
Every non key attribute is fully depend on the primary key (remove partial dependencies)
Anomalies
INSERT
UPDATE

7. Break down the relation FIRST into:
SECOND(sid, status, city) and SP(sid,pid,QTY)

8. 3NF Elimination of transitive dependencies Still anomalies are there
DELETE
UPDATE
That’s why SP is further breakdown to :
SC(sid, city)
CS(city, status)

9. BCNF A relation is said to be in BCNF iff: It is in 3NF
All its determinants (i.e the attributes on which other attribute depends) are candidate keys
First (sid, status,city,pid,qty)--- not in BCNF
SECOND(sid, status, city)
SP(sid,pid,QTY)
SC(sid, city)
CS(city, status)

12. Trivial − If a functional dependency (FD) X → Y holds, where Y is a subset of X, then it is called a trivial FD. Trivial FDs always hold. Non-trivial − If an FD X → Y holds, where Y is not a subset of X, then it is called a non-trivial FD.
Examples:
AA
ABA
ABC

15. More examples R={A,B,C,D,E} {A->B,B->C,C->D,D->E,E->A)
A-Prime attribute
B,C,D- Non Prime attribute
{AB->C,C->D, D->E,A->B}

16. 4NF A relation is said to be in 4NF iff It is in 3NF or BCNF
It does not contain any multi value dependencies

17. Multivalue dependency
It is the dependancy where one attribute value is a multi-value fact about another.
a) {customer_name, address}
customer_name -> -> address
Address <- <- customer_name
b) {Course, student_name, Text_book}
Course -> -> student_name
Course -> -> Text_book
c) {Emp_id,Language, Skill}
Emp_id -> -> Language
Emp_id -> -> Skill
Will result in spurious tuples

18. EMPID
LANGUAGE
SKILL
101
English
Teaching
Hindi
Conversation
202
Singing

19. Rule to transform a relation into 4NF
A relation R having A, B,C as attributes can be non loss decomposed into two projections R1(A,B) and R2(A,C) iff:
MVD A-> -> B/C holds in R

20. 5NF A relation is said to be in 5NF iff Relation is in 4NF
It can n’t be further non loss decomposed