The following queries produce the same results.
SELECT DISTINCT Customer_Name, Customer_City
FROM Customer, Salesman
WHERE Customer.Salesman_ID = Salesman.Salesman_ID
and Salesman.Lname = 'SMITH';

SELECT Customer_Name, Customer_City
FROM Customer
WHERE Customer.Salesman_ID =
(SELECT Salesman_ID
FROM Salesman
WHERE Lname = 'SMITH');

Question

The following queries produce the same results.
SELECT DISTINCT Customer_Name, Customer_City
FROM Customer, Salesman
WHERE Customer.Salesman_ID = Salesman.Salesman_ID
and Salesman.Lname = 'SMITH';

SELECT Customer_Name, Customer_City
FROM Customer
WHERE Customer.Salesman_ID =
(SELECT Salesman_ID
FROM Salesman
WHERE Lname = 'SMITH');

Quizplus · Accepted Answer

Both queries use a join to retrieve customer information based on the last name of a salesman. The first query uses an explicit join, while the second query uses a subquery to retrieve the salesman ID. Both queries produce the same results.

The Following Queries Produce the Same Results