File Upload Field

Hi everyone, Newbie here. I've managed to almost complete a simple db script that writes to and reads from MySQL. When I call an existing entry with mysql_fetch_array and populate the form with the data from the db, it's fine except the file upload field. Each time I try and edit an entry, it overwrites my image file upload (with blank). If I check the source, my file upload field does have the correct data, but how can I tell the form to not overwrite this particular field: <input type="file" name="art" value="<? echo $art_name ?>"> Hope I'm being clear... TIA @lvin