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;
					END WHILE;
					SET minutes=minutes+TIMESTAMPDIFF(MINUTE,next_day,end_day);
					IF ((DAYOFWEEK(start_day)=7) OR (DAYOFWEEK(start_day)=1)) THEN
							SET minutes=minutes+TIMESTAMPDIFF(MINUTE,start_day,CONVERT(CONCAT(SUBSTRING(start_day FROM 1 FOR 10),' 17:30:00'),DATETIME));
					END IF;
			END IF;
			RETURN minutes;
END;

 没考虑中午休息时间