SQL Introduction

Basics :

• SQL stands for Structured Query Language and it is generally referred to as SEQUEL.

• It is used for storing and managing data in relational database management system (RDMS).

• It enables a user to create, read, update and delete relational databases and tables.

• All the RDBMS like MySQL, Informix, Oracle, MS Access and SQL Server use SQL as their standard database language QL allows users to query the database in a number of ways, using English-like / human readable statements.

• SQL commands are instructions which are used to communicate with the database.

• It is also used to perform specific tasks, functions, and queries of data.

• SQL can perform various tasks like create a table, add data to tables, drop the table, modify the table, set permission for users.

History :

• SQL was developed by IBM in the 1970s.

• The American National Standards Institute (ANSI) published its first SQL standard in 1986 and a second widely adopted standard in 1989.

• ANSI released updates in 1992, known as SQL92 and SQL2, and again in 1999, termed both SQL99 and SQL3.

• Each time, ANSI added new features and incorporated new commands and capabilities into the language.

Rules :

• Structure query language is not case sensitive.

• Generally, keywords of SQL are written in uppercase.

• Statements of SQL are dependent on text lines.

• We can use a single SQL statement on one or multiple text line.

• Using the SQL statements, you can perform most of the actions in a database.

• SQL depends on tuple relational calculus and relational algebra