--定义变量
DECLARE @startTime DATETIME
DECLARE @endTime DATETIME
DECLARE @HOUR INT
DECLARE @MINUTE INT
DECLARE @SECOND INT
DECLARE @Minutes VARCHAR

--为变量赋值
SET @startTime = '2020-02-10 08:30:00'
SET @endTime = '2020-02-19 17:10:09'
 
SET @HOUR = DATEDIFF(HOUR, @startTime, @endTime)
SET @MINUTE = DATEDIFF(MINUTE, @startTime, @endTime)
SET @SECOND = DATEDIFF(SECOND, @startTime, @endTime)
SET @Minutes = CASE WHEN DATEPART(SECOND, @endTime) >= DATEPART(SECOND, @startTime)
                    THEN CAST((@MINUTE % 60) AS VARCHAR)
                    ELSE
                    CAST((DATEDIFF(MINUTE, DATEADD(MINUTE, -1, @endTime), @endTime) % 60) AS VARCHAR)
                    END

--SELECT
SELECT  [DD:HH:MM:SS] = CAST((@HOUR / 24) AS VARCHAR) +':'+ CAST((@HOUR % 24) AS VARCHAR) +':'+ @Minutes + ':' + CAST((@SECOND % 60) AS VARCHAR),
        [字符串格式] = CAST((@HOUR / 24) AS VARCHAR) +N'天 '+ CAST((@HOUR % 24) AS VARCHAR) +N'小时 ' + @Minutes + N'分钟 ' + CAST((@SECOND % 60) AS VARCHAR) + N'秒 '