SQL Views

SQL views are virtual tables that are created using a SELECT statement in SQL. A view is a database object that acts as a filter to the data stored in one or more tables. It is a logical representation of data in a database that can be used to simplify the complexity of data and enhance security.


Views can be created in SQL by using the CREATE VIEW statement. The syntax for creating a view is as follows:

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

Here, view_name is the name of the view, and table_name is the name of the table(s) that the view is based on. The column1, column2, … are the columns that the view will include, and the WHERE clause specifies the condition(s) that the data in the view must satisfy.

Once a view is created, it can be used just like a table in SQL. Queries can be run against the view, and data can be retrieved or modified through the view. However, it is important to note that views do not store any data themselves. Instead, they are simply a way to access and manipulate data stored in one or more tables.


ALTER VIEW statement is used to modify an existing view. The ALTER VIEW statement provides a way to make changes to the structure or definition of a view without affecting the underlying tables. Here is the basic syntax for the ALTER VIEW statement:

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


To modify a view, you can use the CREATE OR REPLACE statement followed by the VIEW keyword and the view name. This statement allows you to redefine the view without dropping and recreating it. Here’s the basic syntax:

SELECT column1, column2, ...
FROM your_tables
WHERE your_conditions;

Replace your_view_name with the name of your view and adjust the SELECT statement as needed.

There are several advantages to using views in SQL. One of the main benefits is that views can simplify complex queries and make them easier to read and understand. Views can also be used to enhance security by restricting access to certain data. Additionally, views can be used to hide sensitive data from certain users or applications.

In conclusion, SQL views are useful for managing and manipulating data in a database. By creating virtual tables that act as filters to the data stored in one or more tables, views can simplify complex queries, enhance security, and improve the overall functionality of a database.