mysql求2个日期之间的工作日数（周一到周五）

SQL实现2个日期之间的工作日数(MySQL)

限制条件：只能计算同一年的工作日，如果您需要跨年计算，请输入2次即可。

雕虫小技，希望能对你有所帮助。

DROP FUNCTION IF EXISTS `workdaynum`;
DELIMITER $$
CREATE FUNCTION `workdaynum`(`datefrom` date,`dateto` date) 
RETURNS int(20) NO SQL
BEGIN
	declare days int default 1;
	if (datefrom > dateto  or year(datefrom) != year(dateto)) then
	   return -1;
	end if;
	
	set days = 
	   case 
	   when week(dateto)-week(datefrom) = 0 then 
	        dayofweek(dateto) - dayofweek(datefrom) + 1
		  - case 
		    when (dayofweek(datefrom) > 1 and dayofweek(dateto) < 7) then 0
		    when (dayofweek(datefrom) = 1 and dayofweek(dateto) =7) then 2
		    else 1
		    end
	   else (week(dateto)-week(datefrom)-1) * 5
	      + case 
		    when dayofweek(datefrom) = 1 then 5
			when dayofweek(datefrom) = 7 then 0
		    else 7 - dayofweek(datefrom)
			end
		  + case 
		    when dayofweek(dateto) = 1 then 0
			when dayofweek(dateto) = 7 then 5
			else dayofweek(dateto) - 1
			end
	   end;
			 
	   return days;
end$$
DELIMITER ;