SELECT TimeSheets.EmployeeID, Month(WorkDate) as MonthPay , YEAR(WorkDate) AS YearPay,
   SUM(TimeSheets.HoursWorked * A.HourlyRate)  AS LaborDollars
        FROM TimeSheets
              	INNER JOIN WorkerRates A ON A.EmployeeID = TimeSheets.EmployeeID AND RateEffectiveDate <= WorkDate 
			AND RateAddedDate <= WorkDate
	WHERE NOT EXISTS(SELECT 1 FROM WorkerRates WHERE RateEffectiveDate <= WorkDate 
			AND RateAddedDate <= WorkDate AND (RateEffectiveDate > A.RateEffectivedate OR RateAddedDate > A.RateAddedDate))
    GROUP BY TimeSheets.EmployeeID, Month(WorkDate),YEAR(WorkDate)