SQL

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Introduction

Introduction

What is SQL?

  • SQL stands for Structured Query Language.
  • SQL is used to perform C.R.U.D(Create, Retrieve, Update & Delete) operations on relational databases.
  • SQL is a structured query language, which is a computer language for storing, manipulating and retrieving data stored in relational databases.
  • SQL is the standard for the Relation Database System. All relational database management systems like "MYSQL, MS Access, Oracle, Sybase, Informix, Postgres and SQL Server" use SQL as standard database language.
SQL Commands:
DDL - Data Definition Language

DML - Data Manipulation Language

DCL - Data Control Language

DQL - Data Query Language

DDL - Data Definition Language:
CommandDescription
CREATECreates a new table, a view of table, or other object in database
ALTERModifies an existing database object, such as a table
DROP Delete an entire table , a view of a table or other object in the database
DDL - Data Definition Language:
CommandDescription
INSERT Creates a Record
UPDATEModifies a Record
DELETEDelete Record
DCL - Data Control Language:
CommandDescription
GrantGives a privilege to user
Revoke Takes back privileges granted from user
DQL - Data Query Language:
CommandDescription
Select Retrieves certain records from one or more tables