CREATE TABLE loan (cust_id VARCHAR(255), amount INTEGER); CREATE TABLE customer (cust_name VARCHAR(255), cust_id VARCHAR(255))
List the name of all different customers who have some loan sorted by their total loan amount.
    
SQL: SELECT T1.cust_name FROM customer AS T1 JOIN loan AS T2 ON T1.cust_id = T2.cust_id GROUP BY T1.cust_name ORDER BY SUM(T2.amount)