A More Precise DateDiff Function

This will give you the time information about how apart two dates are.CREATE FUNCTION dbo.fnTimeApart
(
@FromTime DATETIME,
@ToTime DATETIME
)
RETURNS @Time TABLE ([year] SMALLINT, [month] TINYINT, [day] TINYINT, [hour] TINYINT, [minute] TINYINT, [second] TINYINT, [millisecond] SMALLINT)
AS
BEGIN
DECLARE@Temp DATETIME,
@Mts INT,
@year SMALLINT,
@month TINYINT,
@day TINYINT,
@hour TINYINT,
@minute TINYINT,
@second TINYINT,
@millisecond SMALLINT

IF @FromTime > @ToTime
SELECT@Temp = @FromTime,
@FromTime = @ToTime,
@ToTime = @Temp

SET@Mts =CASE
WHEN DATEPART(day, @FromTime) <= DATEPART(day, @ToTime) THEN 0
ELSE -1
END + DATEDIFF(month, @FromTime, @ToTime)

SELECT@year = @Mts / 12,
@month = @Mts % 12,
@Temp = DATEADD(month, @Mts, @FromTime)

SELECT@day = datediff(hour, @Temp, @ToTime) / 24,
@Temp = DATEADD(day, @day, @Temp)

SELECT@hour = DATEDIFF(minute, @Temp, @ToTime) / 60,
@Temp = DATEADD(hour, @hour, @Temp)

SELECT@minute = DATEDIFF(second, @Temp, @ToTime) / 60,
@Temp = DATEADD(minute, @minute, @Temp)

SELECT@second = DATEDIFF(millisecond, @Temp, @ToTime) / 1000,
@Temp = DATEADD(second, @second, @Temp),
@millisecond = DATEDIFF(millisecond, @Temp, @ToTime)

INSERT@Time (year, month, day, hour, minute, second, millisecond)
SELECT@year,
@month,
@day,
@hour,
@minute,
@second,
@millisecond

RETURN
ENDAnd to test the functionSELECTd.FromDate,
d.ToDate,
x.*
FROM(
SELECT'19690906' AS FromDate, '19760608' AS ToDate UNION ALL
SELECT'19991231', '20000101' UNION ALL
SELECT'20070207', '20070208' UNION ALL
SELECT'20000131', '20000228' UNION ALL
SELECT'20070202', '20070201' UNION ALL
SELECT'20070207', '20070307' UNION ALL
SELECT'20000131', '20000301' UNION ALL
SELECT'20011231 15:24:13.080', '20020101 17:15:56.343' UNION ALL
SELECT'20011231 17:15:56.343', '20020101 15:24:13.080' UNION ALL
SELECT'20020101 15:24:13.080', '20011231 17:15:56.343' UNION ALL
SELECT'20000131', '20000229'
) AS d
CROSS APPLYdbo.fnTimeApart(d.FromDate, d.ToDate) AS x
ORDER BYd.FromDate,
d.ToDateAnd the output isFromDateToDateyearmonthdayhourminutesecondmillisecond
19690906197606086920000
19991231200001010010000
200001312000022800280000
200001312000022900290000
20000131200003010110000
20011231 15:24:13.08020020101 17:15:56.34300115143263
20011231 17:15:56.34320020101 15:24:13.08000022816736
20020101 15:24:13.08020011231 17:15:56.34300022816736
20070202200702010010000
20070207200702080010000
20070207200703070100000
Peter Larsson
Helsingborg, Sweden