how to build parent-child data table in excel?

Question

I have data in this fashion:

Parent  |  Data
---------------
Root    | AAA  
AAA     | BBB  
AAA     | CCC  
AAA     | DDD  
BBB     | EEE  
BBB     | FFF  
         


        

Answer 1

I have a simpler solution using TreeView object. If you don't mind the order of the nodes to be difference and using MSCOMCTL.OCX, please use below code.

Requires MSOCOMCTL.OCX to be registered.

Consider this data:

Using a TreeView (adding to a UserForm for visualization, code not shown):

Code to dump the tree data (normal module, use TreeToText):

Option Explicit

Private oTree As TreeView

Private Sub CreateTree()
    On Error Resume Next ' <-- To keep running even error occurred
    Dim oRng As Range, sParent As String, sChild As String

    Set oRng = ThisWorkbook.Worksheets("Sheet1").Range("A2") ' <-- Change here to match your Root cell
    Do Until IsEmpty(oRng)
        sParent = oRng.Value
        sChild = oRng.Offset(0, 1).Value
        If InStr(1, sParent, "root", vbTextCompare) = 1 Then
            oTree.Nodes.Add Key:=sChild, Text:=sChild
        Else
            oTree.Nodes.Add Relative:=oTree.Nodes(sParent).Index, Relationship:=tvwChild, Key:=sChild, Text:=sChild
        End If
        '--[ ERROR HANDLING HERE ]--
        ' Invalid (Repeating) Child will have the Row number appended
        If Err.Number = 0 Then
            Set oRng = oRng.Offset(1, 0) ' Move to Next Row
        Else
            oRng.Offset(0,1).Value = sChild & " (" & oRng.Row & ")"
            Err.Clear
        End If
    Loop
    Set oRng = Nothing
End Sub

Sub TreeToText()
    Dim oRng As Range, oNode As Node, sPath As String, oTmp As Variant

    ' Create Tree from Data
    Set oTree = New TreeView
    CreateTree
    ' Range to dump Tree Data
    Set oRng = ThisWorkbook.Worksheets("Sheet1").Range("D2") ' <-- Change here
    For Each oNode In oTree.Nodes
        sPath = oNode.FullPath
        If InStr(1, sPath, oTree.PathSeparator, vbTextCompare) > 0 Then
            oTmp = Split(sPath, oTree.PathSeparator)
            oRng.Resize(, UBound(oTmp) + 1).Value = oTmp
            Set oRng = oRng.Offset(1, 0)
        End If
    Next
    Set oRng = Nothing
    Set oTree = Nothing
End Sub

Output of code (hard code to D2):

If you have a very large data, you better off load the Range to memory first.