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.

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