以月计算日期重叠

Question

Need a bit of help, if you'd be so kind.

In MS Excel, I'm trying to work out the number of months that a student attends university based off of the academic year.

For instance, a student enrolls & finishes university on the following dates:

• 23/06/2018 - 23/06/2020

and there are multiple academic years which the student attends:

• 01/08/2017 - 31/07/2018

• 01/08/2018 - 31/07/2019

• 01/08/2018 - 31/07/2020

I want to calculate how many months the student attends in each academic year:

• 01/08/2017 - 31/07/2018 (1 month)

• 01/08/2018 - 31/07/2019 (12 months)

• 01/08/2018 - 31/07/2020 (11 months)

I've managed to calculate the days using this function:

=MAX(MIN(term_end_date, student_,end_date) - MAX(term_start_date, student_start_date)+1,0)

But, I need months, if possible.

Appreciate the help in advance.

Answer 1

=DATEDIF(A1,B1,”M”) will give the number of whole months between 2 dates (ie, excluding start and end months) where dates are entered in A1 and B1. The “M” signifies that you'd like the information reported in months.

For a more accurate result, try: =(DATEDIF(A1,B1,”D”) / 365) * 12. If the dates span multiple years - including leap years - try dividing by 365.25 vs 365.

Answer 2

Please try this UDF.

Function MonthsOverlap(Rng As Range, _
                       AccYear As Integer) As String
    ' 016

    Const Ststart As Long = 1               ' index of array 'Study'
    Const Stend As Long = 2                 ' index of array 'Study'

    Dim Fun As Integer                      ' Months of overlap
    Dim YearStart As Date, YearEnd As Date
    Dim Study As Variant

    YearStart = DateSerial(AccYear, 8, 1)   ' modify year and day as required
    YearEnd = DateAdd("yyyy", 1, YearStart)
    Study = Rng.Value                       ' Rng columns must be adjacent

    With Application.WorksheetFunction
        If Study(1, Ststart) <= YearStart Then
            Fun = DateDiff("m", .Max(Study(1, Ststart), YearStart), .Min(Study(1, Stend), YearEnd))
        ElseIf Study(1, Ststart) <= YearEnd Then
             Fun = DateDiff("m", .Max(Study(1, Ststart), YearStart), YearEnd)
        End If
        Fun = .Max(Fun, 0)
    End With

    MonthsOverlap = Fun & " month" & IIf(Fun = 1, "", "s")
End Function

I tested it in a sheet like the one pictured below. Please observe the formula in the Formula Bar.

As you see, the function returns unexpected results for the years 2017 and 2019. I don't think they are wrong. The formula just uses rounding of months different from your system. I think the function can be modified to accommodate your rule once you make it known. Meanwhile it follows Microsoft's rule which, frankly, I also don't know. However, observe that the total time of study is 24 months which is correct and therefore sufficient, in conjunction with a look at the clock, to convince me to let good be good enough for today:-)

Answer 3

I found a solution which works a treat:

Thanks for all your help everyone.