How to add column in a gridview dynamically

If you are binding the grid from the database via datatable like

 DataTable dt = new DataTable();
        dt =//get data from the database in the dt
        gridview1.datasource = dt;
        gridview1.databind();


then you can add the column in the dt and bind the grid again

        dt.Columns.Add("NewColumn");
        dt.AcceptChanges();
        //Again bind it to the gridview
        gridview1.datasource = dt; gridview1.databind();