Summary  
This chapter covers the concept of SQL views—virtual tables defined by reusable queries that simplify complex joins and aggregations, provide a consistent interface over underlying tables, and restrict access to sensitive data.  

General domain of usage  
Data reporting and access control in databases

**Video: Understanding SQL Views and Their Benefits**

This video introduces the concept of SQL views, demonstrating how they are used to simplify complex queries and provide an additional layer of security. You will see examples based on typical business tables, such as `employees` and `sales`, and learn when and why to use views in your database projects.

Views in SQL are **virtual tables** that are defined by a query. Instead of storing data themselves, views present data from one or more tables in a specific format, making it easier to work with complex queries or to expose only certain parts of the data to users. You can create a view using the `CREATE VIEW` statement, and then query it just like a regular table.

Suppose you have two tables: `employees` and `sales`. You might want to frequently see each employee's name along with the total sales they have made. Rather than writing a complex join and aggregation every time, you can define a view that does this for you. Once the view is created, you simply select from it as needed.

-- Drop the view if it already exists to ensure a fresh creation
DROP VIEW IF EXISTS employee_total_sales;

-- Create a view that shows each employee's name and their total sales
CREATE VIEW employee_total_sales AS
SELECT
    e.name AS employee_name,
    SUM(s.amount) AS total_sales
FROM
    employees e
LEFT JOIN
    sales s ON e.employee_id = s.employee_id
GROUP BY
    e.name;

-- Query the view to see the results
SELECT * FROM employee_total_sales;

Views are useful in several scenarios. When you have a complex query that you need to use repeatedly, a view lets you save it and refer to it as if it were a table, making your SQL code easier to read and maintain. **Views also provide abstraction:** users can access only the columns and rows exposed by the view, without needing to know the underlying table structures or relationships. This abstraction is especially valuable for **security**, as you can restrict users' access to sensitive data by giving them permission to access only certain views rather than the base tables themselves.

Master advanced SQL concepts including ACID properties, query optimization, indexing, triggers, window functions, and data control. This course is designed for learners with a solid SQL foundation who want to deepen their understanding and practical skills in optimizing queries and leveraging advanced database features.

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Master advanced SQL features including triggers, window functions, types of window functions, Data Control Language, views, and an introduction to NoSQL.

Views

1. What is a view in SQL?

2. Can you update data through a view?

3. How do views enhance security?