SQLSERVER 得出指定月的工作日天数（没有考虑国家法定假日，只排除周六周日）

--获取指定月的工作日天数（不考虑国家法定节假日，只排除周六周日， 已在休假行事历中设置休息天的也能获得工作天数）
CREATE FUNCTION [dbo].[getCountOfWorkdaysOfMonth](@year_in NVARCHAR(4), @month_in NVARCHAR(2), @restDayStr NVARCHAR(100)) --year_in 为四位年，month_in为两位月，@restDayStr为休息天字符串（用逗号分隔）
returns INT --使用函数的前要先写 set datefirst 1 这一句，让一周的第一天为1，即周一
AS
BEGIN
     IF(@year_in IS NULL OR @month_in IS NULL)
     BEGIN
          RETURN NULL
     END   

     DECLARE @firstDayOfMonth VARCHAR(10) --该月的第一天 yyyy-MM-dd格式
     DECLARE @howManyDaysOfMonth INT --该月有多少天
     DECLARE @dayCusor NUMERIC --循环用的迭代变量
     DECLARE @countOfWorkdaysOfMonth INT --该月的工作日总数，初始化为0
     DECLARE @dayOfADay VARCHAR --某天为周几 用来判断某天是否为周末
     DECLARE @dateOfADay DATETIME --某天的日期 用来获取某天为周几，初始化为该月第一天的日期
     
     SET @firstDayOfMonth = @year_in + '-' + @month_in + '-' + '01'
     SET @dateOfADay = CONVERT(DATETIME,@firstDayOfMonth,121)
		 SET @howManyDaysOfMonth = CAST(DAY(DATEADD(MONTH, DATEDIFF(MONTH, 0, @dateOfADay) + 1, 0) - 1) AS INT)

     IF (@restDayStr IS NOT NULL)
     BEGIN
          DECLARE @strLength INT
          DECLARE @charindexOfComma INT
          DECLARE @separator VARCHAR(1)
          DECLARE @countOfRestDaysOfMonth INT
          
          SET @separator = ','
          SET @charindexOfComma = CHARINDEX(@separator,@restDayStr)
          SET @strLength = LEN(@restDayStr)
          SET @countOfRestDaysOfMonth = 1
          SET @countOfWorkdaysOfMonth = @howManyDaysOfMonth - @countOfRestDaysOfMonth

          WHILE @charindexOfComma > 0
          BEGIN
               SET @countOfRestDaysOfMonth = @countOfRestDaysOfMonth + 1
               SET @restDayStr = SUBSTRING(@restDayStr, @charindexOfComma + 1, @strLength)
               SET @charindexOfComma = CHARINDEX(@separator,@restDayStr)
          END
          
          SET @countOfWorkdaysOfMonth = @howManyDaysOfMonth - @countOfRestDaysOfMonth
     END
     ELSE
     BEGIN
					 SET @countOfWorkdaysOfMonth = 0
					 SET @dayCusor = 1
					 
					 WHILE @dayCusor <= @howManyDaysOfMonth
					 BEGIN
								SET @dayOfADay = DATEPART(WEEKDAY,@dateOfADay)
								IF @dayOfADay <> '6' AND @dayOfADay <> '7'
								BEGIN
										 SET @countOfWorkdaysOfMonth = @countOfWorkdaysOfMonth + 1
								END
								SET @dateOfADay = @dateOfADay + 1
								SET @dayCusor = @dayCusor + 1
					 END
     END

     RETURN @countOfWorkdaysOfMonth
END

参考：
http://wenku.baidu.com/link?url=fB3F0xZmwig9r2M_1pK4BGN6VcHPW6F3NZuABWU4ye6edhxEZQ0Tue5cOFJRzk1rMo6PPZ1iHdfACxCwRsPqAwzvheuvj7o_L994LQYArZS

http://www.cnblogs.com/xionglee/articles/1444916.html