How can I add "dropdownlist" while editing gridview row? Asp.net , C#

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C#

ASP.NET

Gridview

How can i add "dropdownlist" values in gridview which i inserted values in gridview manually,not from database,Remember,there is no database connectivity.Here is my gridview image image
When i enter values and press "Insert" button then values inserted in gridview but when i click on edit button then in "Data Type" column shows "textbox" but i want "data type" column show "dropdownlist" which shows in blow gridview "dropdownlist".I don't want to add extra column using template field etc..

What I have tried:

here is my "Rowedit" event code aspx.cs code :

protected void GridView2_RowEditing(object sender, GridViewEditEventArgs e)
       {

               DataTable t = (DataTable)Session["MyDataTable"];

              GridView2.EditIndex = e.NewEditIndex;

               GridViewRow row = GridView2.Rows[e.NewEditIndex];
              // DropDownList DropDownList2 = (DropDownList)row.FindControl("DropDownList1");
               GridView2.DataSource = t;
               GridView2.DataBind();
            }