auto add colum date modified in foder

le_hieu 

Please test carefully. It will be slow!

Sub AddColumn()
    ' Change the path to that of the folder with the csv files
    Const fld = "C:\MyFiles\"
    ' The exact name of the date modified column
    Const col = "Date Modified"
    Dim fil As String
    Dim wbk As Workbook
    Dim wsh As Worksheet
    Dim rng As Range

    Application.ScreenUpdating = False
    Application.DisplayAlerts = False

    ' Find the first file name
    fil = Dir(fld & "*.csv")
    ' Loop as long as we find a file
    Do While fil <> ""
        ' Open the csv file
        Set wbk = Workbooks.Open(fld & fil)
        ' Reference to its worksheet
        Set wsh = wbk.Worksheets(1)
        ' Try to find the column name
        Set rng = wsh.Rows(1).Find(What:=col, LookAt:=xlWhole, MatchCase:="False")
        If rng Is Nothing Then
            ' If not found, get the next available column
            Set rng = wsh.Cells(1, wsh.Columns.Count).End(xlToLeft).Offset(0, 1)
            ' Set the column header
            rng.Value = col
            ' Save and close the workbook
            wbk.Close SaveChanges:=True
        Else
            ' Otherwise, close the csv file without saving it
            wbk.Close SaveChanges:=False
        End If
        ' Get the next file name
        fil = Dir
    Loop

    Application.DisplayAlerts = True
    Application.ScreenUpdating = True
End Sub