SQL Views
SQL CREATE VIEW Statement
In SQL, a view is a virtual table based on the result-set of an SQL statement.
A view contains rows and columns, just like a real table. The fields in a view are fields from one or more real tables in the database.
You can add SQL statements and functions to a view and present the data as if the data were coming from one single table.
A view is created with the CREATE VIEW
statement.
CREATE VIEW Syntax
CREATE VIEW view_name AS
SELECT column1, column2, ...
FROM table_name
WHERE condition;Note: A view always shows up-to-date data! The database engine recreates the view, every time a user queries it.
SQL CREATE VIEW Examples
The following SQL creates a view that shows all customers from Brazil:
Example
CREATE VIEW [Brazil Customers] AS
SELECT CustomerName, ContactName
FROM Customers
WHERE Country = 'Brazil';
We can query the view above as follows:
Example
SELECT * FROM [Brazil Customers];
The following SQL creates a view that selects every product in the "Products" table with a price higher than the average price:
Example
CREATE VIEW [Products Above Average Price] AS
SELECT ProductName, Price
FROM Products
WHERE Price > (SELECT AVG(Price) FROM Products);
We can query the view above as follows:
Example
SELECT * FROM [Products Above Average Price];
SQL Updating a View
A view can be updated with the CREATE OR REPLACE
VIEW statement.
SQL CREATE OR REPLACE VIEW Syntax
CREATE OR REPLACE VIEW view_name AS
SELECT column1, column2, ...
FROM table_name
WHERE condition;The following SQL adds the "City" column to the "Brazil Customers" view:
Example
CREATE OR REPLACE VIEW [Brazil Customers] AS
SELECT CustomerName, ContactName, City
FROM Customers
WHERE Country = 'Brazil';
SQL Dropping a View
A view is deleted with the DROP VIEW
statement.
SQL DROP VIEW Syntax
DROP VIEW view_name;The following SQL drops the "Brazil Customers" view:
Example
DROP VIEW [Brazil Customers];
