I’m trying to figure this out, but it’s driving me insane! How do I calculate in SQL the number of days that are in a specific year between two dates? For example: we have the range date [12/30/2016-01/05/2017]. If I need to find how many days are in 2017 between this range of dates, it would be 5 days. How is that done in SQL?
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Answer
You didn’t specify your dbms, but in general terms:
- Get the 1st day of the @EndDate year i.e. January 1, 2017
- Then calculate the days difference between @FirstOfYear and @EndDate
For example in MySQL, you could use MAKEDATE() to get the first of the year. Then DATEDIFF() to calculate the number of days
SET @StartDate = '2016-12-30'; SET @EndDate = '2017-01-05'; SELECT DateDiff(@endDate, MAKEDATE(Year(@endDate),1)) + 1 AS DaysInEndDateYear
Result:
| DaysDiffValue| | ----------------: | | 5 |
If you also need to handle ranges where both @StartDate and @EndDate are in the same year:
SET @StartDate = '2017-01-05'; SET @EndDate = '2017-03-14'; SELECT CASE WHEN Year(@StartDate) = Year(@EndDate) THEN DateDiff(@EndDate, @StartDate) + 1 ELSE DateDiff(@endDate, MAKEDATE(Year(@endDate),1)) + 1 END AS DaysInEndDateYear
Results:
| DaysInEndDateYear | | ----------------: | | 69 |
db<>fiddle here