Question

Consider the schema below that models a bank’s branches, customers and their accounts and loans. Provide SQL queries to answer the questions that follow.

Branch (bank_name, addr, city, assets) // Primary Key=bank_name

Customer (cust_name, addr, city) // Primary Key=cust_name

Account (acc_num, cust_name, bank_name, type, balance) // Primary Key=acc_num

Loan (loan_num, cust_name, bank_name, type, amount)  // Primary Key=loan_num

-- 2. Find the names of all the customers who live in a city with no bank branches.

-- a) Use a nested subquery.

-- b) Use a correlated subquery.

Answer 1

2) a) SELECT cust_name FROM Customer WHERE city NOT IN (SELECT city FROM Branch);

2) b) SELECT cust_name FROM Customer WHERE city NOT EXISTS (SELECT city FROM Branch);

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