Normalization-II

In our previous lecture we discussed

Most of all basics of the Relational databases

Objectives of Normalization

Modification anomalies includes Deletion Anomaly and Insertion Anomaly also Updation Anomaly

Functional Dependencies and  Fully Functional Dependencies with Armstrong’s axioms of FD etc.

Now we have to talk about Normalization and  Different forms of normalization.

Normalisation is

  • Refinement of the database specifically ER model.
  • Process of removing the anomalies of database/s and also
  • Segregation of data over many entities or relations.

Need for Normalisation

  • Improves database design.
  • Ensures minimum redundancy of data.
  • To make database structure flexible
  • Reduces need to reorganize data when design is modified or enhanced.
  • To achieve consistency  as a result Removes modification anomalies.  So, Normalized model converted to physical database tables.

Classes of Relation

Relation can be classified by the types of modification anomalies to which they are vulnerable.

The classes of relations and techniques for preventing anomalies are called normal forms.

Depending on its structure, a relation might be in first normal form, second normal form, and third normal form or some other normal form.

E.F. Codd defined first, second, and third normal forms (1NF, 2NF and 3NF). Later, Boyce-Codd normal form (BCNF) was postulated, and then fourth and fifth normal forms were designed.

Thus a relation that is in second form is also in first normal form. A relation in 5NF is also in 4NF, BCNF, 3NF, 2NF and 1NF.

First Normal Form (1NF)

Every relation is, by definition, in first normal form. That is because a relation, has no repeating groups in it – that is the characteristic of the first normal form.

In easy words, only one value is associated with each attribute and the value is not a set of values or a list of values.

Furthermore, Let us study with the help of example about this non repeating group characteristic

Anomalies in 1NF

The first normal form was related to the structure of the representation but the second normal form is related to eliminate data redundancy in these relations.

Before going to 2NF let us discuss the problems of 1NF. The problems can be listed as.

  • Deletion anomaly
  • Insertion anomaly
  • Updation anomaly

Computer Organization

Software Engineering

Programming With C

Published by

Gagan Deep

FOUNDER & DIRECTOR, ROZY COMPUTECH SERVICES, KUK, KURUKSHETRA (HARYANA), INDIA I am in the profession of teaching in Computer Science since 1996.  In 1996, established a professional setup “Rozy Computech Services” for providing Computer Education, computer hardware and software services. In this span of 21 years , in conjunction with Rozy’s, I also associated in Teaching with different Institutions like Assistant Professor in University College, Kurukshetra University, Kurukshetra, Guest Faculty in Directorate of Distance Education, Kurukshetra University, Visiting Faculty in University Institute of Engineering & Technology, Kurukshetra University and a Resource person in EDUSAT, Haryana. Besides, I am also serving as Guide and Mentor in various private educational institutions. Also written 7 books on computer science.

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