3 SQL Query Examples to Create Views Quickly

There are three kinds of Views in SQL. The three views are Read-only, Force, and Updatable. Views real usage is to hide data. And you need to ensure base tables are present before you create a View.

You can call views as logical tables. The advantage of Views is you can show only some of the fields of base tables.

What is a View in SQL

• A view can be constructed with another view so it is called a nested view.
• You can create or replace an existing view
• A view can be created without having base tables. This is possible with the FORCE option.

#1: Read-Only Views

The standard syntax for the view is as follows:

CREATE OR replace VIEW invoice_summary AS
SELECT vendor_name count(*) AS invoice_count,
SUM(invoice_total) AS invoice_total_sum
FROM vendor
JOIN invoices
ON vendors.vendor_id*invoices.vendor_id
GROUP BY vendor_name;

Notes: You cannot update Read-only Views

#2: Force Views

CREATE FORCE VIEW products_list
AS
SELECT product_description,
product_price
FROM products;

Notes: Without base Table you can create a FORCE View.

#3: Updatable Views

A view can be updatable if a view follows certain rules.

A view when it is created for update purpose, you can give INSERT, UPDATE and DELETE operations.

A read-only view should contain WITH  READ ONLY clause

While updating a view, it is possible to update only one base table at a time. When you created a view from more than one table, then it is not possible to update two tables at a time.

How to Manipulate Views 

ALTER View

• CREATE OR REPLACE statement you can use to ALTER the View.

Drop View

• Drop view vendor_sw

Summary

A view with CHECK OPTION restricts to update. When condition satisfied it updates.