Story of SQL Views ideas you need when can be updated

A view can be read-only or updatable. You can maintain data security with views. Creating a view need base tables present in the database. Views are also called logical tables.

What is View

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

Read Only Views

The standard syntax for 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;

Force Views

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

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.

What is ALTER View

Using CREATE OR REPLACE statement you can ALTER the view already present.

Drop View

DROP VIEW vendors_sw

The view vendors_sw is deleted from database.

The Bottom Line

A view with CHECK OPTION is surely help you to satisfy certain condition. Usually this option will be used in updatable views.