Views --updatable view -- dont update view directly if the view is composed of multiple tables-- use instead of trigger for updating such table

 Views are virtual table which have saved quarries. NOTE: VIEWS don't CONTAIN DATA

ADVANTAGES OF VIEWS:

 1. views can be used to reduce the complexity of database schema.

2. views can be used as a mechanism to implement row and column level security.

3. views can be used to present aggregated data and hide detailed data.

syntax:

Create View viewname

as 

select statement

UPdatable views:

you can directly update the view if it is composed of single table .

do not directly update view if it is composed of multiple table  instead use Instead of triggers.