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A Bandb C.: Normalization Is A Database Design Technique That

The document introduces different forms of database normalization: - Normalization organizes tables to reduce redundancy and dependency by dividing larger tables into smaller linked tables. This eliminates redundant data and stores data logically. - There are four normal forms discussed: first, second, third, and Boyce-Codd normal forms. Higher normal forms simplify update semantics and application maintenance. - Functional dependency means an attribute B relies on attribute A such that records with the same A value have the same B value. Partial and transitive dependencies are also introduced.

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97 views2 pages

A Bandb C.: Normalization Is A Database Design Technique That

The document introduces different forms of database normalization: - Normalization organizes tables to reduce redundancy and dependency by dividing larger tables into smaller linked tables. This eliminates redundant data and stores data logically. - There are four normal forms discussed: first, second, third, and Boyce-Codd normal forms. Higher normal forms simplify update semantics and application maintenance. - Functional dependency means an attribute B relies on attribute A such that records with the same A value have the same B value. Partial and transitive dependencies are also introduced.

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james
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BERMUNDO, MELVIN

INTRODUCTION TO NORMALIZATION

NORMALIZATION  is a database design technique that


organizes tables in a manner that reduces redundancy and
dependency of data. Normalization divides larger tables into Figure 2
smaller tables and links them using relationships. The purpose
of Normalization is to eliminate redundant (useless) data and PARTIAL FUNCTIONAL DEPENDENCY:
ensure data is stored logically.
Exists when an attribute B is functionally dependent on an
Four Normal Forms to be discussed; FIRST, SECOND, THIRD attribute A, and A is a component of a multipart candidate
and BOYCE-CODD NORMAL FORMS key.

The benefit of higher normal forms is that update semantics


for the affected data are simplified.

This means that applications required to maintain the


database are simpler.

FUNCTIONAL DEPENDENCY: Figure 3

We say an attribute, B, has a functional dependency FIRST NORMAL FORM:


on another attribute, A, if for any two records, which have the
same value for A, then the values for B in these two records
A relation is in 1NF which the intersection of each row and
must be the same. We illustrate this as:
column contains one and only one value.

B is functionally EmpNum EmpName EmpDegree


A B 101 Jedaiah Bitol BSCpE,MATCS
dependent on A
102 Cyrel Balantocas BSCS,MATCS
Figure 4 : Not in First Normal Form
Wherein ‘A’ is the determinant and ‘B’ is the dependent.

Figure 1

TRANSITIVE FUNCTIONAL DEPENDENCY:

A transitive dependency is when a non-key attribute depends


Figure 5 : In First Normal Form
on another non-key attribute. This is called transitive, because
the primary key is a determinant for another attribute, which
SECOND NORMAL FORM:
in turn is a determinant for a third attribute.
A relation is in 2NF if it is in 1NF, and every non-key attribute
Consider attributes A, B, and C, and where:
is fully dependent on each candidate key. A relation in 2NF
A  B and B  C. will not have any partial dependencies.
Functional dependencies are transitive, which means that we
also have the functional dependency:
AC
We say that C is transitively dependent on A through B.
Figure 6
THIRD NORMAL FORM:
A relation is in 3NF if it is in 2NF and has no transitive
dependencies.

______

Figure 7

BOYCE-CODD NORMAL FORM:

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