主题：删除不重复的值，只保留重复的

显示唯一值，参考

Dim idx As String = "-1,"
Dim idx_temp As String = ""
Dim pdr As DataRow = Nothing
Dim count As Integer = 0
Dim cs As String = "第一列,第二列"
For Each dr As DataRow In DataTables("表A").Select("", cs)
   
    Dim flag As Boolean = False
    If pdr IsNot Nothing Then
        For Each c As String In cs.split(",")
            If pdr(c) <> dr(c) Then
                flag = True
                Exit For
            End If
        Next
    End If
    If flag Then
        If count > 1 Then
            idx &= idx_temp
        End If
        count = 1
        idx_temp = ""
        idx_temp &= dr("_Identify") & ","
    Else
        count += 1
        idx_temp &= dr("_Identify") & ","
    End If
   
    pdr = dr
Next

If count > 1 Then
    idx &= idx_temp
End If

Tables("表A").filter = "_Identify not in (" & idx.trim(",") & ")"