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');
- Names of all the employees with at least one of their customers having a ‘GOOD’ rating.
- Names of all the employees with at most one of their customers having a 'GOOD' rating.
- Names of all the employees with none of their customers having a 'GOOD' rating.
- Names of all the employees with all their customers having a 'GOOD' rating.