Find the name of customers who do not have a loan with a type of Mortgages.
SELECT cust_name FROM customer EXCEPT SELECT T1.cust_name FROM customer AS T1 JOIN loan AS T2 ON T1.cust_id  =  T2.cust_id WHERE T2.loan_type  =  'Mortgages'
customers who do not have a loan of a specific type refers to using EXCEPT to subtract customers with that loan type; loan with a type of Mortgages refers to loan_type = 'Mortgages'; finding customer names refers to SELECT cust_name; joining customer and loan tables to filter specific loans refers to JOIN on cust_id.