来源：http://www.cnblogs.com/kkun/archive/2011/08/17/2143002.html
SELECT
CASE (DATEPART(dw, GETDATE()) + @@DATEFIRST) % 7
WHEN 1 THEN 'Sunday'
WHEN 2 THEN 'Monday'
WHEN 3 THEN 'Tuesday'
WHEN 4 THEN 'Wednesday'
WHEN 5 THEN 'Thursday'
WHEN 6 THEN 'Friday'
WHEN 0 THEN 'Saturday'
END AS DayOfWeekName
DayOfWeekName
-------------
Wednesday