Sweet and simple "first and last" weekday calculation
DECLARE @Year SMALLINT = 2011,
@NumberOfYears TINYINT = 3
;WITH cteCalendar(FirstOfMonth, LastOfMonth)
AS (
SELECT DATEADD(MONTH, 12 * @Year + Number - 22801, 6) AS FirstOfMonth,
DATEADD(MONTH, 12 * @Year + Number - 22800, -1) AS LastOfMonth
FROM master..spt_values
WHERE TYPE = 'P'
AND number BETWEEN 1 AND 12 * @NumberOfYears
)
SELECT DATEADD(DAY, DATEDIFF(DAY, 6, FirstOfMonth) / 7 * 7, 6) AS FirstSunday,
DATEADD(DAY, DATEDIFF(DAY, 5, LastOfMonth) / 7 * 7, 5) AS LastSaturday
FROM cteCalendar