Thử hàm UDF này xem.
Function DocNo(Rng As Range) As String
Dim Arr2(), d&, Lr&, W&, F&, Ngay, Thang, key
Dim Sh As Worksheet, DicDN As Object
Set Sh = Sheets("Issue")
Lr = Rng.Row
Set DicDN = CreateObject("Scripting.Dictionary")
For W = 2 To Lr
If Sh.Cells(W, 3) <> Empty Then...