SQL实现工作日计算

CREATE FUNCTION Time_Span_of_minutes(  

start_day DATETIME,  

end_day DATETIME)  

RETURNS FLOAT 

BEGIN 

            -- 返回按分钟计算两段时间的间隔，采用逐日靠近的方法求解，一天按8小时480分钟计算，周末不计，不考虑法定节假日。  

            -- 如果起始日期在周末，则计算当天时间。  

            DECLARE minutes FLOAT;   

            DECLARE next_day DATETIME;  

            SET minutes=0.0;  

            SET next_day=start_day;  

            IF(TIMESTAMPDIFF(DAY,start_day,end_day)<1.0) THEN 

                    SET minutes=minutes+TIMESTAMPDIFF(MINUTE,start_day,end_day);  

            ELSE 

                    WHILE TIMESTAMPDIFF(DAY,next_day,end_day)>=1.0 DO  

                            IF ((DAYOFWEEK(next_day)=7) OR (DAYOFWEEK(next_day)=1)) THEN 

                                    SET next_day=next_day+INTERVAL 1 DAY;  

                            ELSE 

                                    SET next_day=next_day+INTERVAL 1 DAY;  

                                    SET minutes=minutes+480.0;  

                            END IF;