Calculate time difference in minutes in SQL Server

Use DateDiff with MINUTE difference:

SELECT DATEDIFF(MINUTE, '11:10:10' , '11:20:00') AS MinuteDiff

Query that may help you:

SELECT StartTime, EndTime, DATEDIFF(MINUTE, StartTime , EndTime) AS MinuteDiff 
FROM TableName

Apart from the DATEDIFF you can also use the TIMEDIFF function or the TIMESTAMPDIFF.

EXAMPLE

SET @date1 = '2010-10-11 12:15:35', @date2 = '2010-10-10 00:00:00';

SELECT 
TIMEDIFF(@date1, @date2) AS 'TIMEDIFF',
TIMESTAMPDIFF(hour, @date1, @date2) AS 'Hours',
TIMESTAMPDIFF(minute, @date1, @date2) AS 'Minutes',
TIMESTAMPDIFF(second, @date1, @date2) AS 'Seconds';

RESULTS

TIMEDIFF : 36:15:35
Hours : -36
Minutes : -2175
Seconds : -130535

The following works as expected:

SELECT  Diff = CASE DATEDIFF(HOUR, StartTime, EndTime)
                    WHEN 0 THEN CAST(DATEDIFF(MINUTE, StartTime, EndTime) AS VARCHAR(10))
                    ELSE CAST(60 - DATEPART(MINUTE, StartTime) AS VARCHAR(10)) +
                        REPLICATE(',60', DATEDIFF(HOUR, StartTime, EndTime) - 1) + 
                        + ',' + CAST(DATEPART(MINUTE, EndTime) AS VARCHAR(10))
                END
FROM    (VALUES 
            (CAST('11:15' AS TIME), CAST('13:15' AS TIME)),
            (CAST('10:45' AS TIME), CAST('18:59' AS TIME)),
            (CAST('10:45' AS TIME), CAST('11:59' AS TIME))
        ) t (StartTime, EndTime);

To get 24 columns, you could use 24 case expressions, something like:

SELECT  [0] = CASE WHEN DATEDIFF(HOUR, StartTime, EndTime) = 0
                        THEN DATEDIFF(MINUTE, StartTime, EndTime)
                    ELSE 60 - DATEPART(MINUTE, StartTime)
                END,
        [1] = CASE WHEN DATEDIFF(HOUR, StartTime, EndTime) = 1 
                        THEN DATEPART(MINUTE, EndTime)
                    WHEN DATEDIFF(HOUR, StartTime, EndTime) > 1 THEN 60
                END,
        [2] = CASE WHEN DATEDIFF(HOUR, StartTime, EndTime) = 2
                        THEN DATEPART(MINUTE, EndTime)
                    WHEN DATEDIFF(HOUR, StartTime, EndTime) > 2 THEN 60
                END -- ETC
FROM    (VALUES 
            (CAST('11:15' AS TIME), CAST('13:15' AS TIME)),
            (CAST('10:45' AS TIME), CAST('18:59' AS TIME)),
            (CAST('10:45' AS TIME), CAST('11:59' AS TIME))
        ) t (StartTime, EndTime);

The following also works, and may end up shorter than repeating the same case expression over and over:

WITH Numbers (Number) AS
(   SELECT  ROW_NUMBER() OVER(ORDER BY t1.N) - 1
    FROM    (VALUES (1), (1), (1), (1), (1), (1)) AS t1 (N)
            CROSS JOIN (VALUES (1), (1), (1), (1)) AS t2 (N)
), YourData AS
(   SELECT  StartTime, EndTime
    FROM    (VALUES 
                (CAST('11:15' AS TIME), CAST('13:15' AS TIME)),
                (CAST('09:45' AS TIME), CAST('18:59' AS TIME)),
                (CAST('10:45' AS TIME), CAST('11:59' AS TIME))
            ) AS t (StartTime, EndTime)
), PivotData AS
(   SELECT  t.StartTime,
            t.EndTime,
            n.Number,
            MinuteDiff = CASE WHEN n.Number = 0 AND DATEDIFF(HOUR, StartTime, EndTime) = 0 THEN DATEDIFF(MINUTE, StartTime, EndTime)
                                WHEN n.Number = 0 THEN 60 - DATEPART(MINUTE, StartTime)
                                WHEN DATEDIFF(HOUR, t.StartTime, t.EndTime) <= n.Number THEN DATEPART(MINUTE, EndTime)
                                ELSE 60
                            END
    FROM    YourData AS t
            INNER JOIN Numbers AS n
                ON n.Number <= DATEDIFF(HOUR, StartTime, EndTime)
)
SELECT  *
FROM    PivotData AS d
        PIVOT 
        (   MAX(MinuteDiff)
            FOR Number IN 
            (   [0], [1], [2], [3], [4], [5], 
                [6], [7], [8], [9], [10], [11],
                [12], [13], [14], [15], [16], [17], 
                [18], [19], [20], [21], [22], [23]
            ) 
        ) AS pvt;

It works by joining to a table of 24 numbers, so the case expression doesn't need to be repeated, then rolling these 24 numbers back up into columns using PIVOT