Views in SQL

Views

In SQL, a view is a virtual table that represents the result set of a SQL query. Unlike a physical table, a view does not store data itself but rather provides a way to retrieve and manipulate data from one or more tables in a structured and reusable manner. Views are often used to simplify complex queries, enhance security by restricting access to specific data, and present data in a particular format.

Creating a View:

To create a view, you use the CREATE VIEW statement, which defines the view's name and the query that generates its content.

Syntax:

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

view_name: The name of the view.

column1, column2, etc.: The columns to include in the view.

table_name: The table(s) from which the data is retrieved.

condition: Optional filter criteria to narrow down the result set

Example:

Suppose you want to create a view that lists the first names and last names of employees with a salary greater than $50,000:

CREATE VIEW high_salary_employees AS
SELECT first_name, last_name
FROM employees
WHERE salary > 50000;

Querying a View:

Once a view is created, you can query it as if it were a table:

SELECT * FROM high_salary_employees;

This query retrieves all the rows and columns defined in the high_salary_employees view.

Dropping a View:

If you no longer need a view, you can remove it using the DROP VIEW statement:

DROP VIEW high_salary_employees;