根据年份和周数，获得该周的星期一

        DECLARE @year NVARCHAR(4),@weekday INT
        SET @year = '2015'
        SET @weekday = 2

PRINT CASE WHEN DATEPART(WEEKDAY, @year + '-01-01') = 2 
           THEN DATEADD(WEEK, @weekday - 1, @year + '-01-01') 
           WHEN DATEPART(WEEKDAY, @year+ '-01-01') = 1 
           THEN DATEADD(WEEK, @weekday - 2, DATEADD(D, 9 - datepart(weekday, @year + '-01-01'), @year+ '-01-01')) 
           ELSE DATEADD(WEEK, @weekday- 1, DATEADD(D, 9 - datepart(weekday, @year+ '-01-01'), @year+ '-01-01')) END