Two Dependent Combo Boxes - excel

Question

**Edit:** Managed to find the solution to it thanks to fellow user #Tin Bum
I'm trying to make 2 Combo Box where the the first one (Cmb1) will show only unique values from Column 1 and then (Cmb2) will show a list of values from Column 2 that are related to Column 1.
Populating the Cmb1 has been successful however the problem lies with populating Cmb2.
Column 1 Column 2
1 a
1 b
1 c
2 d
2 e
The problem lies with populating Cmb2
Private Sub UserForm_Activate()
Dim wslk As Worksheet
Set wslk = Worksheets("w1")
With wslk
t1 = .Cells(Rows.Count, "B").End(xlUp).Offset(1, 0).row
On Error Resume Next
For y = 2 To t1
Set c = .Cells(y, 2)
Set t1rng = .Range(.Cells(2, 2), .Cells(y, 2))
x = Application.WorksheetFunction.CountIf(t1rng, c)
If x = 1 Then Cmb1.AddItem c
Next y
On Error GoTo 0
End With
End Sub
Private Sub Cmb1_Change()
Dim wslk As Worksheet
Set wslk = Worksheets("w1")
Private Sub Cmb1_Change()
Dim wslk As Worksheet
Set wslk = Worksheets("w1")
Cmb2.ListIndex = -1
If Cmb1.ListIndex > -1 Then
'Currently I am stuck over here
Cmb2.List =
**Solution:**
Dim i As Integer
Cmb2.Clear
For i = 2 To wslk.Range("B" & Application.Rows.Count).End(xlUp).row
If wslk.Range("B" & i).Value = Cmb1.Value Then
Cmb2.AddItem wslk.Range("C" & i)
End If
End If
End Sub

Answer 1

This the bones of a solution for the Exit Event Code.
It should be Ok for hundreds of rows but may be slow for thousands of rows, also you still have to workout the 2 ranges - I've arbitrarily assigned them to fixed ranges.
On the plus side it should be simple to follow
Dim Rng1 As Range, Rng2 As Range
Dim xCel As Range, List2 As String
Rng1 = Range("A10:A20") ' whatever Range covers your Col1 Data
Rng2 = Range("B10:B20") ' whatever Range covers your Col2 Data
List2 = ""
For Each xCel In Rng2.Cells
If xCel.Offset(0, -1).Value = Combobox1.Value Then
' Add this Value to a String using VbCrLf as a Separator
List2 = IIf(List2 = "", "", List2 & vbCrLf) & CStr(xCel.Value)
End If
Next xCel
' Split the String into an Array of Values for ComboBox2
ComboBox2.List = Split(List2, vbCrLf)
It also relies on NOT HAVING CHR(13) & CHR(10) (VbCrLF) in your data

Answer 2

You could use a Dictionary to get your unique values and also populate this on your Initialize Sub. Making this a Public variable in the scope of the Userform will allow you to then use it later on the Change event as well to get your list values
Option Explicit
Private Uniques As Object
Private Sub UserForm_Initialize()
Dim c As Range, InputRng As Range
Dim tmp As Variant
Dim k As String
Set Uniques = CreateObject("Scripting.Dictionary")
With Worksheets("w1")
Set InputRng = .Range(.Cells(2, 2), .Cells(.Cells(.Rows.Count, 2).End(xlUp).Row, 2))
For Each c In InputRng
k = c.Value2
If Uniques.exists(k) Then
tmp = Uniques(k)
ReDim Preserve tmp(LBound(tmp) To UBound(tmp) + 1)
tmp(UBound(tmp)) = c.Offset(0, 1).Value2
Uniques(k) = tmp
Else
ReDim tmp(0)
tmp(0) = c.Offset(0, 1).Value2
Uniques.Add Key:=k, Item:=tmp
End If
Next c
Cmb1.List = Uniques.keys
End With
End Sub
Private Sub Cmb1_Change()
Cmb2.ListIndex = -1
If Cmb1.ListIndex > -1 Then
Cmb2.List = Uniques(Cmb1.Value)
End If
End Sub

Answer 3

Private Sub Cmb1_Change()
Dim wslk As Worksheet
Set wslk = Worksheets("w1")
Dim i As Integer
Cmb2.Clear
For i = 2 To wslk.Range("B" & Application.Rows.Count).End(xlUp).row
If wslk.Range("B" & i).Value = Cmb1.Value Then
Cmb2.AddItem wslk.Range("C" & i)
End If