SQL Tutorial for Beginners: SQL Views

Learn about SQL Views with the help of examples. Learn how to create and use SQL views to simplify your queries and restrict access to your data. 

In SQL, views contain rows and columns similar to a table, however, views don't hold the actual data.

You can think of a view as a virtual table environment that's created from one or more tables so that it's easier to work with data.

Example: SQL Views

Creating a View in SQL

We can create views in SQL by using the CREATE VIEW command. For example,

CREATE VIEW us_customers AS
SELECT customer_id, first_name
FROM Customers
WHERE Country = 'USA';

Here, a view named us_customers is created from the customers table.

Now to select the customers who lives in USA, we can simply run,

SELECT *
FROM us_customers;

Updating a View

It's possible to change or update an existing view using the CREATE OR REPLACE VIEW command. For example,

CREATE OR REPLACE VIEW us_customers AS
SELECT *
FROM Customers
WHERE Country = 'USA';

Here, the us_customers view is updated to show all the fields.

Deleting a View

We can delete views using the DROP VIEW command. For example,

DROP VIEW us_customers;

Here, the SQL command deletes the view named us_customers.

Note: If the view is not available, the above command throws an error.

Views for Complex Queries

Suppose A and B are two tables and we wan't to select data from both of the tables. For that, we have to use SQL JOINS.

However using the JOIN each time could be a tedious task. For that, we can create a view to fetch records easily.

Let's create a view,

CREATE VIEW order_details AS
SELECT Customers.customer_id, Customers.first_name, Orders.amount
FROM Customers
JOIN Orders
ON Customers.customer_id = Orders.customer_id;

Now, to select the data, we can run

SELECT *
FROM order_details;

Here, the SQL command selects data from the view order_details.

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