Relational Database Model: Normalization and Steps in Normalization (Especially for GATE-Geospatial 2022)

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Relational Database Model

The relational model used the basic concept of a relation or table. The columns or fields in the table identify the attributes such as name, age, and so. A tuple or row contains all the data of a single instance of the table such as a person named Doug.

The relational model is the conceptual basis of relational databases. Proposed by E. F. Codd in 1969, it is a method of structuring data using relations, which are grid-like mathematical structures consisting of columns and rows. Codd proposed the relational model for IBM, but he had no idea how extremely vital and influential his work would become as the basis of relational databases. Most of us are very familiar with the physical manifestation of a relation in a database - it is called a table.

Lecture 2

A relational database is a collection of tables which can be connected to each other by keys. A relation is defined as a set of tuples that have the same attributes. A tuple usually represents an object and information about that object. Objects are typically physical objects or concepts. A relation is usually described as a table, which is organized into rows and columns. All the data referenced by an attribute are in the same domain and conform to the same constraints.

The relational model specifies that the tuples of a relation have no specific order and that the tuples, in turn, impose no order on the attributes. Applications access data by specifying queries, which use operations such as select to identify tuples, project to identify attributes, and join to combine relations.

Normalization

Normalization is the process of breaking down a table into small tables while maintaining the necessary linkages between them.

Purpose

  • To avoid redundant data in the table.
  • To maintain and update data effectively in the separate tables.
  • To facilitate distributed database.

Steps in Normalization

First Normal Form

In this form the tables don՚t have multiple values in the cell (as comma separated list) .

This Table Shows First Step in Normalization

Second Step

Break down the table into small ones, some redundancy remains.

This Image Shows Break down the Table into Small Ones

Separate tables from the second step in normalization. The keys relating the tables are highlighted.

Final Step

New tables are created no redundancy exists.

This Image Shows Separate Tables After Normalization

Separate tables after normalization. The keys relating the tables are highlighted.

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