俺把代码贴出来吧：

Dim dl as string = "产品|客户|雇员"
Dim tr As WinForm.TreeView
Dim nd,nd1,nd2,nd3 As WinForm.TreeNode
tr = e.Form.Controls("TreeView1")    \'Forms("窗口1").Controls("TreeView1")   
tr.Nodes.Clear
for i as integer = 0 to dl.split("|").length-1
    nd = Tr.Nodes.Add("Root & i","按" & "" & dl.split("|")(i) & "")
    Dim pcas As List(Of String)
    pcas = DataTables("订单").GetUniqueValues("", "" & dl.split("|")(i) & "")
    For ii As integer = 0 to pcas.count-1
        nd1 = nd.Nodes.Add("Sub & ii+1","" & pcas(ii) & "")
        if i+1<=dl.split("|").length-1
            dim f as string = "[" & dl.split("|")(i) & "] = \'" & nd1.text & "\' "
            Dim cas As List(Of String) = DataTables("订单").GetUniqueValues( f ,"" & dl.split("|")(i+1) & "")
            for iii as integer = 0 to cas.count-1
                nd2 = nd1.Nodes.Add("Sub & iii+1","" & cas(iii) & "")
                if i+2=dl.split("|").length-1
                    dim f1 as string = "[" & dl.split("|")(i+1) & "] = \'" & nd2.text & "\'"
                    Dim ca As List(Of String) = DataTables("订单").GetUniqueValues(f & "and " & f1 ,"" & dl.split("|")(i+2) & "")
                    for iiii as integer = 0 to ca.count-1
                        nd3 = nd2.Nodes.Add("Sub & iiii+1","" & ca(iiii) & "")
                    next
                end if
                if i+2-dl.split("|").length+1 = 1
                    dim f1 as string = "[" & dl.split("|")(i+1) & "] = \'" & nd2.text & "\'"
                    Dim ca As List(Of String) = DataTables("订单").GetUniqueValues(f & "and " & f1 ,"" & dl.split("|")(0) & "")
                    for iiii as integer = 0 to ca.count-1
                        nd3 = nd2.Nodes.Add("Sub & iiii+1","" & ca(iiii) & "")
                    next
                end if
            next
        else
            dim f as string = "[" & dl.split("|")(i) & "] = \'" & nd1.text & "\' "
            Dim cas As List(Of String) = DataTables("订单").GetUniqueValues(f ,"" & dl.split("|")(0) & "")
            for iii as integer = 0 to cas.count-1
                nd2 = nd1.Nodes.Add("Sub & iii+1","" & cas(iii) & "")
                dim f1 as string = "[" & dl.split("|")(0) & "] = \'" & nd2.text & "\'"
                if i+2-dl.split("|").length-1 = 0
                    Dim ca As List(Of String) = DataTables("订单").GetUniqueValues(f & "and " & f1 ,"" & dl.split("|")(1) & "")
                    for iiii as integer = 0 to ca.count-1
                        nd3 = nd2.Nodes.Add("Sub & iiii+1","" & ca(iiii) & "")
                    next
                end if
            next
        end if
    Next
next

总觉得很繁琐，应该可以简化的，可是俺功底不足， 看看其他前辈和狐友的了。

厉害！