for each dc1 As datacol in datatables("Zstb").datacols for each dc As datacol in datatables("Zszy").datacols if dc1.name = dc.name then Exit For else Dim Len As Integer = DataTables("Zszy").DataCols(dc.name).MaxLength DataTables("Zstb").DataCols.Add(dc.name, GetType(string),len) end if next next