What is a view in the context of databases and what is it used for?

A view is a virtual table based on the result of an SQL query. It does not store data physically but provides a stored query that can be used as a regular table.

Applications of views:

• Simplifying complex queries: A complex SELECT can be defined as a view, and then accessed as a simple table.
• Restricting data access: A view can be created to show only certain columns or rows of the underlying tables, providing users with only the necessary information.
• Creating abstractions: A view can hide the complexity of the underlying data structure, presenting it in a more convenient form.
• Enhancing security: Access can be granted to a view instead of direct access to the underlying tables.

Example of creating a view:

CREATE VIEW ActiveCustomers AS
SELECT customer_id, name, email
FROM customers
WHERE status = 'active';

Now, data can be selected from ActiveCustomers as if it were a regular table:

SELECT name, email
FROM ActiveCustomers;