SQL Introduction


SQL Introduction

I) What is SQL?

•    SQL stands for Structured Query Language

•    SQL was initially developed at IBM in 1970s

•    SQL is used to communicate with a database.
 

•    According to ANSI (American National Standards Institute), it is the standard language for relational database management systems.


II) Who should learn SQL?
 

•    Database developers

•    Database Testers

•    Database Administrators

III) Usage of SQL?
 

•    SQL is used to create new databases

•    SQL is used to create new tables in a database
 

•    SQL is used to insert records in a database
 

•    SQL is used to update records in a database
 

•    SQL is used to delete records from a database
 

•    SQL is used to retrieve data from a database
 

•    SQL is used to execute queries against a database
 

•    SQL can set permissions on tables, procedures, and views
 

•    SQL is used to create stored procedures in a database
 

•    SQL is used create views in a database

IV) What are the Sub sets of SQL?

•    Data definition Language

•    Data Manipulation Language

•    Data Control Language

V) Data definition Language

A DDL is a language used to define data structures within a database.

Create: To create databases and database objects

Alter: To modify existing database object

Drop: To drop databases and database objects

Truncate: To remove all records from a table

Rename: To rename database objects

VI) Data Manipulation Language

Select: To select specific data from a database

Insert: To insert new records in a table

Update: To update existing records

Delete: To delete existing records from a table

VII) Data Control Language

Grant: To provide access on the Database objects to the users

Revoke: To remove user access rights to the database objects

Deny: To deny permissions to a User.

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