How do you create and execute views in MySQL?

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In MySQL, a view is a virtual table that contains the results of a SELECT query. Views allow you to simplify complex queries by encapsulating them into a reusable object. Here's how you can create and execute views in MySQL:

Creating a View:

To create a view, you can use the CREATE VIEW statement followed by the view name and the SELECT query that defines the view. Here's the basic syntax:

sql code
CREATEVIEW view_name ASSELECT column1, column2, ... FROM table_name WHEREcondition;

Example: Let's say you have a table called employees with columns id, name, and salary. You want to create a view that shows the names and salaries of employees earning more than $50,000.

sql code
CREATEVIEW high_earning_employees ASSELECT name, salary FROM employees WHERE salary >50000;

Executing a View:

Once you've created a view, you can query it like you would with a regular table:

sql code
SELECT*FROM high_earning_employees;

This query will retrieve the names and salaries of employees earning more than $50,000 from the high_earning_employees view.

Remember, views are read-only. You can't perform INSERT, UPDATE, or DELETE operations on a view directly unless it's a "simple" view (a view that includes exactly one table and doesn't use GROUP BY or HAVING clauses).

Modifying a View:

You can modify an existing view using the CREATE OR REPLACE VIEW statement. For example:

sql code
CREATEOR REPLACE VIEW high_earning_employees ASSELECT name, salary FROM employees WHERE salary >60000;

In this example, the high_earning_employees view is modified to include employees with a salary greater than $60,000.

Dropping a View:

To remove a view, you can use the DROP VIEW statement:

sql code
DROPVIEW view_name;

Replace view_name with the name of the view you want to drop.

Remember to replace table and column names with your actual table and column names in the examples above.

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