Don't upload file if entry greater than ""?

EDIT: Title makes no sense It should say: Upload file if entry does not equal ""

I am having an issue when creating a form for modifying an entry.

This is what I have:

the form:

echo "<tr><td>Rendering Image:</td><td><input type=\"file\" name=\"rendering\" /></td><td></td></tr>\n";

Code (markup):

the upload or using old entry:

$filetomodify = mysql_query("SELECT * FROM homes WHERE modelnumber='$_POST[modelnumber]'");
$filetomodify = mysql_fetch_array($filetomodify);    
    
//UPLOAD RENDERING PICTURE IF ONE WAS CHOSEN ELSE USE CURRENT ONE
if($_FILES['rendering'] != "") {
$filename1 = "rend-".$_POST['collection'].$_POST['modelnumber']."-".strtolower($_FILES['rendering']['name']);
move_uploaded_file($_FILES['rendering']['tmp_name'], $_SERVER['DOCUMENT_ROOT']."/homes/".$filename1);
} else {
$filename1 = $filetomodify['renderingimg'];
}

Code (markup):

What I need it to do it upload and replace the old entry in the database if you chose a file in the form. If you didn't choose a file and left the rendering image input blank then I want it to just use whatever is already in the database.

Thank you in advance.

 

figured it out never mind.

I was looking for an array to be blank but the value is going to be array unless I specify a name. For anyone running across this thread you fix the above code by replacing.

if($_FILES['rendering'] != "")

with:

if(strtolower($_FILES['rendering']['name']) != "")