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Question

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’);

a.

Names of all the employees with at least one of their customers having a ‘GOOD’ rating.

b.

Names of all the employees with at most one of their customers having a ‘GOOD’ rating.

c.

Names of all the employees with none of their customers having a ‘GOOD’ rating.

d.

Names of all the employees with all their customers having a ‘GOOD’ rating.

Answer: (d).Names of all the employees with all their customers having a ‘GOOD’ rating.

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Q. Consider the following relational schema: employee(empId, empName, empDept) customer(custId, custName, salesRepId, rating) salesRepId is a foreign key referring to...

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