How to hide a column (GridView) but still access its value?

Question

I have a GridView with a DataSource (SQL Database). I want to hide a column, but still be able to access the value when I select the record. Can someone show me

Answer 1

When I want access some value from GridView before GridView was appears.

1. I have a BoundField and bind DataField nomally.
2. In RowDataBound event, I do some process in that event.

3. Before GridView was appears I write this:

   protected void GridviewLecturer_PreRender(object sender, EventArgs e) 
   {
       GridviewLecturer.Columns[0].Visible = false;
   }