CROSS JOIN and SELF JOIN

CROSS JOIN

SELECT s.name, sub.subject
FROM students s
CROSS JOIN subjects sub;

SELF JOIN

SELECT e.name AS employee, m.name AS manager
FROM staff e
JOIN staff m ON e.manager_id = m.id;

Summary

• CROSS JOIN = every combination (Cartesian product).
• SELF JOIN = a table joined to itself using aliases.

CROSS JOIN

SELECT s.name, sub.subject
FROM students s
CROSS JOIN subjects sub;

SELF JOIN

SELECT e.name AS employee, m.name AS manager
FROM staff e
JOIN staff m ON e.manager_id = m.id;

सारांश

• CROSS JOIN = हर combination (Cartesian product)।
• SELF JOIN = aliases से table को खुद से जोड़ना।