**Course Title:** SQLite Mastery: Lightweight Database Management **Section Title:** Views, Triggers, and Advanced Features **Topic:** Creating and managing views in SQLite **Introduction** In SQLite, a view is a virtual table based on the result set of a SQL query. Views are useful for simplifying complex queries, hiding sensitive data, and providing a layer of abstraction between the physical database structure and the application code. In this topic, you will learn how to create and manage views in SQLite. **Creating a View** To create a view in SQLite, you use the `CREATE VIEW` statement followed by the name of the view and the SQL query that defines it. The basic syntax is as follows: ```sql CREATE VIEW view_name AS SELECT column1, column2, ... FROM table_name WHERE condition; ``` Here is an example of creating a view that lists all the customers from the United States: ```sql CREATE VIEW us_customers AS SELECT * FROM customers WHERE country = 'USA'; ``` Once the view is created, you can query it just like any other table: ```sql SELECT * FROM us_customers; ``` **Managing Views** You can use the `DROP VIEW` statement to delete a view: ```sql DROP VIEW view_name; ``` However, before dropping a view, you need to ensure that no other views or queries depend on it. **View Types** SQLite supports two types of views: 1. **Simple views**: These views are based on a single table and do not use aggregate functions or subqueries. 2. **Complex views**: These views can be based on multiple tables, use aggregate functions, or include subqueries. **View Properties** Views in SQLite have the following properties: * **Virtual tables**: Views are not physical tables and do not store any data. * **Read-only**: Views are read-only, meaning you cannot insert, update, or delete data directly from a view. * **Updatable views**: However, if the underlying table is updatable, you can update the data through a view by defining an `INSTEAD OF` trigger (more on this later). **Best Practices** When creating and managing views in SQLite, follow these best practices: * Use meaningful and descriptive names for your views. * Document your views, including the underlying query and any dependencies. * Use views to simplify complex queries and improve code readability. * Avoid using views that are too complex or recursive, as they can impact performance. **Real-World Example** Suppose you have an e-commerce database with a `orders` table that contains all the orders made by customers. You want to create a view that shows the total sales for each region. Here's how you can do it: ```sql CREATE VIEW regional_sales AS SELECT region, SUM(total_amount) AS total_sales FROM orders GROUP BY region; ``` You can then query the `regional_sales` view to get the total sales for each region: ```sql SELECT * FROM regional_sales; ``` **Conclusion** In this topic, you learned how to create and manage views in SQLite. Views are a powerful feature in SQLite that can simplify complex queries, hide sensitive data, and provide a layer of abstraction between the physical database structure and the application code. By following the best practices outlined above, you can effectively use views to improve your database design and application performance. **What's Next?** In the next topic, you will learn about triggers and their use cases in SQLite. **Resources:** * [SQLite Documentation: CREATE VIEW](https://sqlite.org/lang_createview.html) * [SQLite Documentation: DROP VIEW](https://sqlite.org/lang_droptable.html) **Leave a comment/ask for help**: If you have any questions or need help with creating and managing views in SQLite, feel free to leave a comment below.