How calculate age using two dates

On a form I have two date fields (formatted as short date).  One is Date1, and the other is Date2.

Then there is a third field named Age.

Age needs to be calculated by using Date2 minus Date1.

For example. is Date1 is 1/1/2010 and Date2 is 1/7/2014 then the result in Age should be 4 (a whole number).

What would the code be for the afterupdate event of Date2?
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Try this:

Age = Abs(datediff("yyyy",Date2,Date1))

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EirmanChief Operations ManagerCommented:
You've described it yourself already ..... Date2 minus Date1
and use the INT function to change it to a whole number

Various methods are described here ...

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SteveL13Author Commented:
Neither suggestion is working.  

With Age = Abs(datediff("yyyy",Date2,Date1)) I get 114

With the other suggestion I get 115
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Double check that there are no typos in your dates, such as 2104 mistakenly used for 2014.

If you try this from the command line, it definitely gives you the correct results (4):

Debug.Print Abs(datediff("yyyy",#1/1/2010# ,#1/7/2014#))
EirmanChief Operations ManagerCommented:
Have a look at the attached sheet
Dates are in UK format
EirmanChief Operations ManagerCommented:
The yellow section is Just in case you don't want to use today's date and you want a fixed date for calculation.
If we are talking about a person's age, usually we try to be more accurate.  So a person born in June doesn't reach his "age" until June of the year.  So from Jan to May, his age is x and from June to Dec, it is y.  Try these two functions.  You'll have to change the first to take a second argument rather than assuming today as the second date.

Public Function CalculateAge(DOB As Date) As Integer
    Dim WorkDate As Date
    Dim RawAge As Integer
    RawAge = DateDiff("yyyy", DOB, Date)
    WorkDate = DateSerial(Year(Date), month(DOB), Day(DOB))
    CalculateAge = RawAge + (Date < WorkDate) '(Date < WorkDate) = 0 or -1
End Function

Function CalculateLongAge(DOB As Date, CurDate As Date) As String
    Dim Y As Integer
    Dim M As Integer
    Dim D As Integer
    Dim Temp1 As Date
    Temp1 = DateSerial(Year(CurDate), month(DOB), Day(DOB))
    Y = Year(CurDate) - Year(DOB) + (Temp1 > CurDate)
    M = month(CurDate) - month(DOB) - (12 * (Temp1 > CurDate))
    D = Day(CurDate) - Day(DOB)
    If D < 0 Then
        M = M - 1
        D = Day(DateSerial(Year(CurDate), month(CurDate) + 1, 0)) + D + 1
    End If
    CalculateLongAge = Y & " years " & M & " months " & D & " days"
End Function

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SteveL13Author Commented:
To PatHartman:

I'd like to try this but I'm not sure what to change or where.

My two fields are "DOB" and "DOP"  (Date of Birth and Date of Passing)

The third field I want calculated is "Age".

How do I code this?
The first function takes in only one input - the DOB and ASSUMES the other date will be the current date.  You would change the function to take two dates as input and any place in the code where the Date function is used, you would replace with the name of the DOP field.

The second function already takes two dates.

Public Function CalculateAge(DOB As Date, DOP As Date) As Integer
    Dim WorkDate As Date
    Dim RawAge As Integer
    RawAge = DateDiff("yyyy", DOB, DOP)
    WorkDate = DateSerial(Year(DOP), month(DOB), Day(DOB))
    CalculateAge = RawAge + (DOP< WorkDate) '(Date < WorkDate) = 0 or -1
End Function

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So to use the first function.
Age = CalculateAge(DOB, DOP)

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Note that there is no error checking in either function.  You should probably add some and decide what you need to do if one of the dates is missing.  You could verify that both dates are populated BEFORE calling the function and display an error message then OR you could verify that both dates are present inside the function.  That makes the function a little less flexible since what ever calls it will have to know how to deal with the error it raises.
EirmanChief Operations ManagerCommented:
Sorry .. I misread the topic area
Interesting.  I thought I had seen Excel as a second topic on this question initially too.
Gustav BrockCIOCommented:
You have to use DateAdd to get it right for any given combo of dates:
Public Function Years( _
  ByVal datDate1 As Date, _
  ByVal datDate2 As Date, _
  Optional ByVal booLinear As Boolean) _
  As Integer

' Returns the difference in full years between datDate1 and datDate2.
' Calculates correctly for:
'   negative differences
'   leap years
'   dates of 29. February
'   date/time values with embedded time values
'   negative date/time values (prior to 1899-12-29)
' Optionally returns negative counts rounded down to provide a
' linear sequence of year counts.
' For a given datDate1, if datDate2 is decreased step wise one year from
' returning a positive count to returning a negative count, one or two
' occurrences of count zero will be returned.
' If booLinear is False, the sequence will be:
'   3, 2, 1, 0,  0, -1, -2
' If booLinear is True, the sequence will be:
'   3, 2, 1, 0, -1, -2, -3
' If booLinear is False, reversing datDate1 and datDate2 will return
' results of same absolute Value, only the sign will change.
' This behaviour mimics that of Fix().
' If booLinear is True, reversing datDate1 and datDate2 will return
' results where the negative count is offset by -1.
' This behaviour mimics that of Int().

' DateAdd() is used for check for month end of February as it correctly
' returns Feb. 28. when adding a count of years to dates of Feb. 29.
' when the resulting year is a common year.
' 2000-11-03. Cactus Data ApS, CPH.
' 2000-12-16. Leap year correction modified to be symmetrical.
'             Calculation of intDaysDiff simplified.
'             Renamed from YearsDiff() to Years().
' 2000-12-18. Introduced cbytMonthDaysMax.
' 2007-06-22. Version 2. Complete rewrite.
'             Check for month end of February performed with DateAdd()
'             after idea of Markus G. Fischer.

  Dim intDiff   As Integer
  Dim intSign   As Integer
  Dim intYears  As Integer
  ' Find difference in calendar years.
  intYears = DateDiff("yyyy", datDate1, datDate2)
  ' For positive resp. negative intervals, check if the second date
  ' falls before, on, or after the crossing date for a full 12 months period
  ' while at the same time correcting for February 29. of leap years.
  If DateDiff("d", datDate1, datDate2) > 0 Then
    intSign = Sgn(DateDiff("d", DateAdd("yyyy", intYears, datDate1), datDate2))
    intDiff = Abs(intSign < 0)
    intSign = Sgn(DateDiff("d", DateAdd("yyyy", -intYears, datDate2), datDate1))
    If intSign <> 0 Then
      ' Offset negative count of years to continuous sequence if requested.
      intDiff = Abs(booLinear)
    End If
    intDiff = intDiff - Abs(intSign < 0)
  End If
  ' Return count of years as count of full 12 months periods.
  Years = intYears - intDiff
End Function

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PS: Miriam, you know this.
Bill RossProgrammerCommented:

Here is a function that I use that's pretty clear:

Public Function AgeCalc(vDate1 As Date, vBirthDate As Date) As Long
    On Error Resume Next
    If Month(vDate1) < Month(vBirthDate) Or (Month(vDate1) = Month(vBirthDate) And Day(vDate1) < Day(vBirthDate)) Then
        AgeCalc = Year(vDate1) - Year(vBirthDate) - 1
        AgeCalc = Year(vDate1) - Year(vBirthDate)
    End If
End Function

Essentially if their birthday has past then math works - if not then subtract one year.




SteveL13Author Commented:
I had a typo which is why this wasn't working.  Once I fixed it... it worked!  Thanks.
Gustav BrockCIOCommented:
So this was Excel? So why put it under Access?
SteveL13Author Commented:
It was Access.  But I used

"Date2 minus Date1
and use the INT function to change it to a whole number"

to get to the solution.
Gustav BrockCIOCommented:
Are you serious? That's not a solution - except for sending birthday cards or so.

EirmanChief Operations ManagerCommented:
Thanks for the points SteveL13

and my commiserations to all those who produced some great code/solutions without due reward.
SteveL13Author Commented:
It did solve the problem.  See attachment.
Gustav BrockCIOCommented:
"Solve" is a strong word here. For example for this day, 2014-01-09, this method fails for those born on:

2013-01-09     1             0
2009-01-09     5             4
2005-01-09     9             8
2001-01-09     13            12
1997-01-09     17            16
1993-01-09     21            20
1989-01-09     25            24
1985-01-09     29            28
1981-01-09     33            32
1977-01-09     37            36
1973-01-09     41            40
1969-01-09     45            44
1965-01-09     49            48

Left coloumn is the correct age, right is the result from the expression.

Just a sample.
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