Unable to hide gridview column using MappingType.Hidden on dataset column

I am creating a c# web project with a gridview used to display data.  I do not want several of the columns in the dataset displayed but do need programmatic access to the data so am unable to set the visible attribute as this seems to unbind the data.

The gridview is declared as:

<asp:GridView ID="GridView1" runat="server" AllowPaging="True" AllowSorting="True"
onselectedindexchanged="GridView1_SelectedIndexChanged" DataKeyNames="ID"
EmptyDataText="No matching items found.">
<Columns>
      <asp:CommandField ShowSelectButton="True" />
</Columns>
</asp:GridView>

In the page load event I have the following code to load.  The problem is all the columns are displayed in the gridview regardless of weather I set the columnmapping attribute to hidden or not.

using (MySqlConnection cnDB = new MySqlConnection("server=localhost;user id=root;password=pwd;persist security info=True;database=test"))
            {
                MySqlDataAdapter oResultsAdapter = new MySqlDataAdapter("select * from job", cnDB);
                oResultsAdapter.SelectCommand.CommandType = CommandType.Text;
                cnDB.Open();
                DataSet dsResults = new DataSet();
                oResultsAdapter.Fill(dsResults, "Results");
                oResultsAdapter.Dispose();
 
                foreach (DataColumn c in dsResults.Tables["Results"].Columns)
                {
                    if (!c.ColumnName.Equals("Lot") || !c.ColumnName.Equals("ID"))
                        c.ColumnMapping = System.Data.MappingType.Hidden;
                }
 
                GridView1.DataSource = dsResults.Tables["Results"];
                GridView1.DataBind();

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