dropdownlist select a row when the id is the same in row id to fill it

dropdownlist select a row when the id is the same in row id to fill it

I use this syntax to fill dropdownlist from database but i want to select
a row if the ID is the same
command.CommandText = "select area_name from area where area_name !='' and
cast (gov_id as varchar) ='" + DropDownList1.SelectedValue + "'";
The problem is the dropdown list is empty