protected void gv_RowDataBound(object sender, GridViewEditEventArgs e)
{
   if (e.Row.RowType == DataControlRowType.DataRow)
      {
            if ((e.Row.RowState & DataControlRowState.Edit) > 0)
            {
              DropDownList DStatusEdit= (DropDownList)e.Row.FindControl("DStatusEdit");
              DataTable dt = con.GetData("select distinct status from directory");
              DStatusEdit.DataSource = dt;
              DStatusEdit.DataTextField = "status";
              DStatusEdit.DataValueField = "status";
              DStatusEdit.DataBind();
              DataRowView dr = e.Row.DataItem as DataRowView;
              DStatusEdit.SelectedValue = dr["columnname"].ToString();
            }
       }
    }
 }

    protected void gv_RowEditing(object sender, GridViewEditEventArgs e)
    {
      gv.EditIndex = e.NewEditIndex;
      gridviewBind();// your gridview binding function
    }