Join Conditions & Syntax

Join Conditions and Syntax

Always provide a proper condition in the ON clause to avoid Cartesian joins unless explicitly intended.

-- Good practice
SELECT e.first_name, d.department_name
FROM employees e
JOIN departments d ON e.department_id = d.department_id;

-- Bad practice: Missing ON clause leads to large result set
SELECT * FROM employees, departments;

Using table aliases improves readability.