Updating and Deleting Views

Introduction

In MySQL, a view is a virtual table based on the result-set of an SQL statement. When you create a view, you encapsulate the query. It stores the SQL statement in the MySQL server and allows you to use it over and over again. In this article, we are going to learn how to update and delete views in MySQL.

Updating a View in MySQL

To update a view in MySQL, you use the CREATE OR REPLACE VIEW statement. The CREATE OR REPLACE VIEW statement helps in updating the view. If the view exists, it is replaced; if it does not exist, a new one is created.

Here is the syntax:

CREATE OR REPLACE VIEW view_name AS
SELECT columns
FROM table_name
WHERE conditions;

In this syntax, view_name is the name of the view that you want to update, table_name is the name of your table, columns are the names of the columns and conditions are the conditions to meet.

Let's look at an example:

CREATE OR REPLACE VIEW customer_details AS
SELECT customer_name, customer_id
FROM customers
WHERE customer_country = 'USA';

This SQL statement will create or replace a view named customer_details. The view contains the customer_name and customer_id of all customers from the USA.

Deleting a View in MySQL

To delete a view in MySQL, you will use the DROP VIEW statement. This statement helps in deleting a view permanently.

Here is the syntax:

DROP VIEW view_name;

In this syntax, view_name is the name of the view that you want to delete.

Let's look at an example:

DROP VIEW customer_details;

This SQL statement will delete the view named customer_details.

Conclusion

In this article, you've learned how to update existing views using the CREATE OR REPLACE VIEW statement and how to delete views using the DROP VIEW statement in MySQL. Practice these commands on your local system to better understand how they work, and remember, the key to mastering MySQL is continuous practice and implementation. Happy learning!