Structured Query Language

Introduction

The structured query language for SQL language that enables you to create and operate on relational database, which are sets of related information stored in tables.

What is SQL ?

SQL is a simple query language used for accessing, handling and managing data in relational databases.

Processing capabilities of SQL

SQL has proved to be an language that can be used by both casual users as well skilled programmers. It offers a variety of processing capabilities, simpler ones of which may be used by the former and the more complex by the letter class of users.

The various processing capabilities of SQL are:-

1.Data definition language
2.Data manipulation language
3.Embed data manipulation language 4.View definition language
5.Authorization
6.Integrity
7.Transaction control

What is data definition language (DDL) ??

The DDL provides a set of definition to specify the storage structure and access method used by database system.

What is data manipulation language (DML)?

Data manipulation language or DML is a language that enable user to access on manipulate data as organised by appropriate data model.

What is data control language (DCL)?

It is used to control access to the database by providing grant or revoke access permission.

How to create a table in SQL?

In order to create a SQL table you have to use DDL command.
Here is an example of creating a table

Create table <tablename>
(<column name>  <data type>  <size>,
   <column name> <data type> <size>....);

To create an employee table whose scheme is as follows:

employee(ecode,ename,grade,gross)

Solution:   Create Table employee
                 ( ecode integer,
                   ename char(20),
                   grade char(20),
                   gross decimal );

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