Question

I’m trying to extract date/times from strings with the following patterns and convert them to date types in Access.

1. “08-Apr-2012 21:26:49”

2. “…Confirmed by SMITH, MD, JOHN (123) on 4/2/2012 11:11:01 AM;”

Can anyone help?

Answer 1

Add this function to a VBA module:

' ----------------------------------------------------------------------'
' Return a Date object or Null if no date could be extracted            '
' ----------------------------------------------------------------------'
Public Function ExtractDate(value As Variant) As Variant
    If IsNull(value) Then
        ExtractDate = Null
        Exit Function
    End If

    ' Using a static, we avoid re-creating the same regex object for every call '
    Static regex As Object
    ' Initialise the Regex object '
    If regex Is Nothing Then
        Set regex = CreateObject("vbscript.regexp")
        With regex
            .Global = True
            .IgnoreCase = True
            .MultiLine = True
            .pattern = "(\d+\/\d+/\d+\s+\d+:\d+:\d+\s+\w+|\d+-\w+-\d+\s+\d+:\d+:\d+)"
        End With
    End If
    ' Test the value against the pattern '
    Dim matches As Object
    Set matches = regex.Execute(value)
    If matches.count > 0 Then
        ' Convert the match to a Date if we can '
        ExtractDate = CDate(matches(0).value)
    Else
        ' No match found, jsut return Null '
        ExtractDate = Null
    End If
End Function

And then use it like this, for instance in a query:

SELECT ID, LogData, ExtractDate(LogData) as LogDate
FROM   MyLog

Make sure you check that hte dates returned are in the proper format and make sense to you.
CDate() interprets the date string in different ways depending on your locale.

If you’re not getting the desired result, you will need to modify the code to separate the individual components of the date and rebuild them using DateSerial() for instance.