[Resolved] MySQL Calculation or calc after result set?

[lobster]

Have a table that holds the price of a vessel and the NADA price of a vessel (both ints)

I need to return the top 25 of highest % below NADA

Here's the formula:
(NADA price - listing price) / NADA price * 100

My confusion lies on where to start with this. should I calculate this from the db and LIMIT 25 in some sort of temporary table (have never done this before) or should I get all data back and then sort and then do a for loop with < 26 ??

$hlist = mysql_query("select * from VESSEL");
 $hrow = mysql_fetch_assoc($hlist);
 $per = ($hrow["NADA"] - $hrow["PRICE"])/ $hrow["NADA"] * 100;
   for($h = 0; $h < 26; $h++){  

result list should look like:
16.21
16.15
15.37
8.60

etc...
The formula works great when I pull back all results..but I cm performing the formula afterward and have no way to sort the result set on it.

I appreciate any help... I am stuck on this.

[lobster]

$hlist = mysql_query("select , ((NADA-PRICE)/NADA 100) AS PER from VESSEL ORDER BY PER desc LIMIT 25");