A TECHNICAL DEEP DIVE INTO SQL JOINS AND WINDOWS FUNCTIONS.

Relational databases are built on relationships between tables. Joins and window functions enable data retrieval and analytics. Joins combine data across tables, window functions enable row-level analytics without collapsing result sets. SQL joins what is a join? A join combines rows from two or more tables based on a related column (usually a foreign key) Types of joins INNER JOIN Returns only matching rows from both tables eg ; show employees with their department name. Only matching rows appear. If an employee had no department, they would be excluded. SELECT e.employee_id, e.name, d.department_name FROM employees e INNER JOIN departments d ON e.department_id = d.department_id; LEFT JOIN Returns all rows from the left table and matched rows from the right table. Non matches become NULL. SELECT d.department_name, e.name FROM departments d LEFT JOIN employees e ON d.department_id = e.department_id; Explanation; every department appears. If a department has no employees, employee colum