LEFT JOIN and RIGHT JOIN

LEFT JOIN

SELECT s.name, c.class_name
FROM students s
LEFT JOIN classes c ON s.class_id = c.class_id;

RIGHT JOIN

SELECT s.name, c.class_name
FROM students s
RIGHT JOIN classes c ON s.class_id = c.class_id;

Summary

• LEFT JOIN keeps all left-table rows; RIGHT JOIN keeps all right-table rows.
• Missing matches become NULL.

LEFT JOIN

SELECT s.name, c.class_name
FROM students s
LEFT JOIN classes c ON s.class_id = c.class_id;

RIGHT JOIN

SELECT s.name, c.class_name
FROM students s
RIGHT JOIN classes c ON s.class_id = c.class_id;

सारांश

• LEFT JOIN सारी left rows रखता है; RIGHT JOIN सारी right rows।
• Missing matches NULL बन जाते हैं।