What is the total sick leave hours of employees who do not wish to receive any e-mail promotion?
Employees who do not wish to receive any e-mail promotions are marked as EmailPromotion = 0
SELECT SUM(T1.SickLeaveHours) FROM Employee AS T1 INNER JOIN Person AS T2 ON T1.BusinessEntityID = T2.BusinessEntityID WHERE T2.EmailPromotion = 0