Intro to DBMS

Introduction to Relational Algebra

Relational Algebra is not actually implemented anywhere. It is a collection of mathematical expressions. So, it is a theoretical or logical model to access the database.

In simple words, we can say that relation Algebra provides the base for SQL and Non-SQL. SQL and Non-SQL are physically implemented. SQL database software are (MySQL, SQL Server, Oracle, Informix, IBM DB2, etc.)

This theoretical database model came in 1970.  This model was developed by EF CODE, which is considered the father of the Database.

Relational Algebra is a procedural query language or formal query language.  In procedural query language, every user has to mention two things to access data.

  1. What to do?
  2. How to do?

Relational Algebra is just like C language, where we have to tell what to do. And how to do it? , before accessing data.

Note: The concept of Relational Algebra and SQL is the same, but the SYNTAX is different. If we understand the operation of Relational Algebra then we easily move to SQL and Non-SQL.

So, we learn Relational algebra before learning SQL and Non-SQL.

Operators in Relational Algebra

Relational Algebra has three types of operators, as in the following diagram.


In upcoming lectures, we will cover all operators one by one