请教一个排列组合的问题 - 专家坐堂 - Foxtable(狐表) - 新一代数据库软件，完美融合Access、Foxpro、Excel、vb.net之优势，人人都能掌握的快速软件开发工具!

Dim ss1 As List(of String) = DataTables("表A").GetUniqueValues("第一列 Is Not Null","第一列")
Dim ss2 As List(of String) = DataTables("表B").GetUniqueValues("第一列 Is Not Null","第一列")
Dim ss3 As List(of String) = DataTables("表C").GetUniqueValues("第一列 Is Not Null","第一列")

DataTables("表D").DataRows.Clear
For Each s1 As String In ss1
For Each s2 As String In ss2
For Each s3 As String In ss3

   Dim r As Row = Tables("表D").AddNew()
   r("第一列") = s1 & "." & s2 & "." & s3
        Next
    Next
Next

主题：请教一个排列组合的问题