[Solved] Break down long multi day periods of time into several single day periods

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The method I have used here is a Tally Table to create extra rows. I JOIN onto the tally table where the number of hours / 24 (integer maths is useful) is greater than the tally number, and then can use that to calculate the hours. 

WITH YourTable AS(
    SELECT *
    FROM (VALUES(1,CONVERT(date,'2018/01/24',111),4 ),
                (2,CONVERT(date,'2018/03/21',111),40),
                (3,CONVERT(date,'2018/08/16',111),33),
                (4,CONVERT(date,'2018/12/01',111),8 ),
                (5,CONVERT(date,'2018/12/17',111),56 ),
                (6,CONVERT(date,'2018/12/17',111),24 ))V(VacationID,VacationDate,VacationDuration_Hr)),
--Solution
N AS(
    SELECT N
    FROM (VALUES(NULL),(NULL),(NULL),(NULL),(NULL))N(N)),
Tally AS(
    SELECT ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) -1 AS I
    FROM N N1, N N2) -- 25 days, add more for more days
SELECT YT.VacationID,
       DATEADD(DAY, T.I, YT.VacationDate) AS VacationDate,
       CASE WHEN VacationDuration_Hr - (T.I * 24) > 24 THEN 24 ELSE YT.VacationDuration_Hr - (T.I * 24) END AS VacationDuration_Hr
FROM YourTable YT
     JOIN Tally T ON (YT.VacationDuration_Hr -1) / 24 >= T.I
ORDER BY YT.VacationID,
         T.I;

You could also use an rCTE here instead, however, I tend to avoid those for things like this; especially when I have no context of what the upper limit to the value of VacationDuration_Hr could be. if it is large it could have some nasty performance implications and a Tally will significantly out perform the RBAR nature of an rCTE.

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solved Break down long multi day periods of time into several single day periods