How to bind data to a DDL present inside a GridView from Database and retain the selection

protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)

{

  if (e.Row.RowType == DataControlRowType.DataRow)

  {

  DropDownList ddlDropDownList = (DropDownList)e.Row.FindControl("ddlDropDownList");

  if (ddlDropDownList != null)

  {

     ddlDropDownList.FindByValue(Convert.ToString(ViewState["selectedvalue"])).Selected = true;    

  }

  }

}