Views

View is a query which is stored in the database to reuse later. Views are nothing but a pseudo table. Views can contain a complex query which retrieves data from multiple tables. So, instead of writing a complex query everytime, you can simply create a view and call it when ever required.

Syntax:

Creating a View:
CREATE VIEW View_name AS 
Query;

How to call view

SELECT * FROM View_name;

Altering a View

ALTER View View_name AS 
Query;

Deleting a View

DROP VIEW View_name;

Example:

Let us consider the below two tables:

CREATE TABLE ORDERS(ORDERID INT,CUSTOMERID VARCHAR(50),ITEM VARCHAR(50),BILL_AMOUNT DECIMAL(10,2));
CREATE TABLE ORDER_HISTORY(ORDERID VARCHAR(50),ITEMS VARCHAR(50),BILL_AMOUNT DECIMAL(10,2),DATE_OF_ORDER DATE);

-- creating view
CREATE VIEW ORD_VIEW AS SELECT O.ORDERID,O.CUSTOMERID,H.ITEM,H.DATE_OF_ORDER from ORDERS O INNER JOIN ORDER_HISTORY H; 

-- to display the view
select * from ORD_VIEW;

In this way, we can also restrict the visibility of columns of the table to the users.