Question

Introduction to IS & IT

IT101

What problems are caused by data redundancy? Can data redundancies be completely eliminated when the database approach is used? Justify your answer in your own words.

Answer 1

Answer:

Data Redundancy occurs when duplicate data is stored in two or more than two separate fields in a database. Due to data redundancy database may have inconsistent data.

Data Redundancy allows storing duplicate data in a database. Data Redundancy occurs when duplicate data is stored in two or more than two separate fields in a database. Inconsistent data may be stored in a database Due to data redundancy.

Problem Caused due to data redundancy:

To make any modification in any field need you to make changes in every duplicate field of a database.

Unnecessary Database size is increased because the database contains duplicate entries.

The cost of database insertion, updating, modification, and maintenance were increased.

The chance of data inconsistency increases because if you make any modification in any particular field but forget to modify the duplicate fields.

Database Approach to eliminate data redundancies:

The database Approach is used to remove all the limitations of a file and improve the accessing, viewing, modification of a database.

Normalization is used to efficiently organizing data in a database. It eliminates data redundancy from the database. Normalization organizes the attributes (Columns) and relation (tables) of a database to ensure their dependency is correctly enforced by database integrity constraints.

The normal form is the set of rules to normalize data.

The first normal form eliminates similar data in individual tables. Each field contains an atomic value. If any fields contain a multi-valued or composite attribute then it decomposes and stores a single value in a field.

A Primary key is used to uniquely identify a record in a table.

The Second normal form eliminates partial dependency from the table. In this, a separate table is created for each set of related data. The tables are related using the foreign key.

The Third normal form eliminates fields that do not depend on the key. It ensures that a table has No transitive functional dependency.

The Boyce-Codd normal form ensures that a table contains not more than one candidate key.

The fourth normal form eliminates relations with multi-valued dependencies.

The Fifth normal form creates relations that cannot be further decomposed.

Using the Normalization redundancy of data is eliminated from a table.