CREATE TABLE customer (credit_score INT, cust_id VARCHAR)
CREATE TABLE loan (credit_score INT, cust_id VARCHAR)

Find the average credit score of the customers who do not have any loan.
SELECT AVG(credit_score) FROM customer WHERE NOT cust_id IN (SELECT cust_id FROM loan)
SELECT AVG("credit_score") FROM "customer" WHERE NOT "cust_id" IN (SELECT "cust_id" FROM "loan")