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      • Views

      A view is a virtual table based on a SQL query. This chapter introduces how to create and use views.

      Create View

      -- Basic view
CREATE VIEW active_users AS
SELECT id, name, email
FROM users
WHERE status = 'active';

-- Query view
SELECT * FROM active_users;

      View with JOIN

      -- View with multiple tables
CREATE VIEW user_orders AS
SELECT 
    u.id,
    u.name,
    o.order_number,
    o.total_amount
FROM users u
JOIN orders o ON u.id = o.user_id;

      Replace View

      -- Replace existing view
CREATE OR REPLACE VIEW active_users AS
SELECT id, name, email, city
FROM users
WHERE status = 'active';

      Drop View

      -- Drop view
DROP VIEW IF EXISTS active_users;

      View Advantages

      1. Simplify complex queries
      2. Security - hide sensitive columns
      3. Reusability
      4. Data abstraction

      View Limitations

      1. Performance overhead
      2. Cannot always update
      3. Depends on base tables

      Summary

      • CREATE VIEW: Create view
      • DROP VIEW: Delete view
      • Views simplify queries
      • Use for security and abstraction

      Next Step: Learn INDEXES