For example, you can find customers whose payments are greater than the average payment using a subquery(Assume all data are in the same table)
a) SELECT customer_id FROM customers WHERE payment > AVG(payment);
b) SELECT customer_id FROM customers HAVING payment > AVG(payment);
c) SELECT customer_id FROM customers WHERE payment > (SELECT AVG(payment) FROM customers);
d) SELECT customer_id FROM customers GROUP BY customer_id HAVING payment > AVG(payment);
