How do I split up a year range into individual years in a given field? - sql

Question

I was working in Access to make a query of a few tables, and realized that a column of a table does not meet a specific requirement.
I have a field that consists of thousands of records, and it contains "years" in the following format (an example) : 1915-1918.
What I want to accomplish is to make that value individual in the records. So
the end result would be : 1915,1916,1917,1918.
Basically, I want to convert 1915-1918 to 1915,1916,1917,1918.
I thought a simple concatenation would suffice, but could not wrap my head around how to make it so that it can do it for all thousands of records. I did some research and reached the conclusion that a user defined function might be the way to go. How would I go about this?

Answer 1

When your field value consists of 4 digits followed by a dash followed by 4 more digits, this function returns a comma-separated list of years.
In any other cases (Null, a single year such as "1915" instead of a year range, or anything else), the function returns the starting value.
Public Function YearList(ByVal pInput As Variant) As Variant
Dim astrPieces() As String
Dim i As Long
Dim lngFirst As Long
Dim lngLast As Long
Dim varReturn As Variant
If pInput Like "####-####" Then
astrPieces = Split(pInput, "-")
lngFirst = CLng(astrPieces(0))
lngLast = CLng(astrPieces(1))
For i = lngFirst To lngLast
varReturn = varReturn & "," & CStr(i)
Next
If Len(varReturn) > 0 Then
varReturn = Mid(varReturn, 2)
End If
Else
varReturn = pInput
End If
YearList = varReturn
End Function
However, this approach assumes the start year in each range will be less than the end year. In other words, you would need to invest more effort to make YearList("1915-1912") return a list of years instead of an empty string.
If that function returns what you want, you could use it in a SELECT query.
SELECT years_field, YearList(years_field)
FROM YourTable;
Or if you want to replace the stored values in your years field, you can use the function in an UPDATE query.
UPDATE YourTable
SET years_field = YearList(years_field);

Answer 2

You can use the Split function to return an array from the "years" field that contains the upper and lower year. Then loop from the lower year to the upper year and build the concatenated string. For example:
Public Function SplitYears(Years As String) As String
Dim v As Variant
Dim i As Long
Dim s As String
v = Split(Years, "-", 2)
If UBound(v) = 1 Then
For i = v(0) To v(1)
s = s & "," & CStr(i)
Next i
s = Right(s, Len(s) - 1)
Else
s = v(0)
End If
SplitYears = s
End Function

Answer 3

In Excel, make a sequential reference table of Years, for the range of years that you expect to encounter.
Next, use left and right functions to get the start and end of the range.
Create an update query and update the target field with a concatenation of target field to itself and then also the reference year values between that also fit between the start and end of the range.
Or I guess you could make a user function.

Answer 4

Add the code below to a module in Visual Basic
Public Function CommaDates(Start_End) As String
Dim strt As String
Dim endd As String
Dim x As Long
strt = Left(Start_End, 4)
endd = Right(Start_End, 4)
CommaDates = strt
For x = strt + 1 To endd
CommaDates = CommaDates & "," & x
Next x
End Function
Call this in a query like NEW_DATE: CommaDates([OLD_DATE_FIELD_NAME])