Views in SQL

A view in SQL is a virtual table that is created based on the result set of a query. It does not store data itself but dynamically generates data when queried. Views can simplify complex queries, enhance security, and improve data abstraction.

Views simplify complex queries, abstract the database structure, and enhance security by exposing only specific data to the user.

Key Features of Views:

1. Virtual Table: A view behaves like a table but does not store data physically.

2. Query Abstraction: Complex queries can be encapsulated in a view, making them easier to use.

3. Security: Views can restrict access to certain columns or rows, providing controlled access to data.

4. Reusability: Once created, a view can be reused in queries as if it were a table.

Syntax:

CREATE VIEW view_name AS
SELECT column1, column2, ...
FROM table_name
WHERE condition;

Example:

CREATE VIEW employee_view AS
SELECT first_name, last_name, department
FROM employees
WHERE department = 'Sales';

This view, employee_view, will return the first name, last name, and department of employees in the Sales department.

Modifying Views:

You can modify a view using the ALTER VIEW statement:

ALTER VIEW view_name AS
SELECT column1, column2, ...
FROM table_name
WHERE condition;

Dropping a View:

To remove a view:

DROP VIEW view_name;