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5 quick tips to solve questions on Normalization for GATE CS || Exam Preparation Simplified

Normalization is an important topic to crack Gate . Experts at GATE – prepladder  shares  5 quick tips to solve questions on normalization.

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For analyzing relations based on their primary key and functional dependencies, Normailization is used. Normalization is often performed as a series of tests on a relation to determine whether it satisfies or violates the requirements of a given normal form.

5 quick Tips to solve Questions on Normalization

#Tip1

1NF =>entry should have at most 1 single value, no repeating group,no 2 rows should be same

#Tip2

2NF => it is related with partial dependencies. A relation is in 2 NF when every non-key attributes are dependent on the candidate key

#Tip3

3NF =>  now this talks about transitive dependencies. It exists when  A-->B-->C  and not  A-->C.In 3NF there should no A->C if A->B and B->C.

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#Tip4

Boyce-Codd Normal Form (BCNF) => checks about determinant. Left side of determined is called determinant. It makes sure all determinants are candidate keys.

#Tip5

4NF => Deals with multi-valued dependencies , X ->> Y means for each value of X, we can have more than one value of Y. It prevents nontrival MVD’s. For 5NF , A relation is in 5 NF if further cannot be non-loss decomposed

Here is process of normalization.

Solved Examples From GATE

Q1.         Consider the following implications relating to functional and multivalued dependencies given below, which may or may not be correct.

1. If A ->> B and A ->> C, then A -> BC
2. If A ->   B and A ->  C then A ->> BC
3. If A ->> BC and A -> B and A ->C
4. If A -> BC and A ->  B   and A ->> C

Exactly how many of the above implications are valid?

A) 0 (B)  1            (C)  2         (D)  3

In DBMS, we can see that

If A   ->->  B and  A->-> C  then A -> BC

And A ->-> BC then     A  ->-> BC

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Q2.         Examine the table shown below.

 branchNo branchAddress telNos B001 8 Jefferson Way, Portland, OR 97201 503-555-3618, 503-555-6534 B002 City Centre Plaza, Seattle, WA 98122 206-555- 6756, 206-555 -8836 B003 14 – 8th Avenue, New York, NY 10012 212 -371 – 3000 B004 16 – 14th Avenue, Seattle, WA 98128 206 – 555 – 3131, 206 – 555 – 4112

• Why is this table not in I NF?
• Describe and illustrate the process of normalizing the data shown in this table to third normal form (3NF)

Soln.

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