Help converting OSC SQL code to Zencart

[mdc]

What error?
And is this correct?
From:

$sql = "SELECT * FROM fastway_zones WHERE $topcode >= f_postcode and $topcode <= f_postcode";
$qResult = tep_db_query($sql); 
$rec = tep_db_fetch_array($qResult);

To:

$sql = "SELECT * FROM fastway_zones WHERE $topcode >= f_postcode and $topcode <= f_postcode";
$qResult = $db->Execute($sql); 
$rec = $db->Execute($qResult);

I'm not so sure about this, i followed the instructions on the wiki.
$my_var_query = tep_db_query("query stuff"); >> $my_var = $db->Execute("query stuff");

$rec = tep_db_fetch_array($qResult); >>$rec = $db->Execute($qResult); (Not sure about this)