Consider the following relational schema: employee(empId,empName,empDept)…

Consider the following relational schema:

employee(empId,empName,empDept)
customer(custId,custName,salesRepId,rating)

salesRepId is a foreign key referring to empId of the employee relation. Assume that each employee makes a sale to at least one customer. What does the following query return?

SELECT empName
FROM employee E
WHERE NOT EXISTS (SELECT custId
                  FROM customer C
                  WHERE C.salesRepId = E.empId
                  AND C.rating <> 'GOOD');