Introduction to SQL

SQL stands for structured query language. SQL is a tool which is used to interact with database in very easier and friendly manner. It provides the functionality of retrieving, updating and deleting the database and applying security and integrity constraints also.SQL originally called ‘Sequel’ and was first developed by IBM. As the time passed, various versions were developed like SQL-86, SQL-89, SQL-92, SQL:1999, SQL:2003, SQL:2006, SQL:2008 and SQL:2011.

Introduction to SQL
Introduction to SQL – Image Source


The SQL language is made up of several parts given below.

1. Data Definition Language (DDL)

The SQL DDL commands allow to define the schema (basic structure) of a table. It allows us to modify and delete the schemas also.


2. Data Manipulation Language (DML)

The SQL DML commands allow us to insert, delete and modify the tuples in the database.


3. Integrity Constraints Commands

These commands are basically part of the DDL commands. These commands allow us to specify integrity constraints. In the coming tutorials I will clear the concepts of integrity constraints with the help of examples.


4. View Definition

Some commands which are the part of DDL commands.


5. Authorization and Security

These DDL commands allow a user to specify the level of rights to access and modify the database. With the proper implication of authorization we can achieve the security in our database.


6. Transaction Control Language (TCL)

The SQL commands allow a user to control the transactions.

This was a brief introduction to SQL. In the next tutorial you will learn about data types in SQL.

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