$dbh->prepare("
    insert into user_master (msisdn,cat0,cat1,cat2,cat3,cat4,cat5,cat6,cat7,vip,SAcode,phone_type)
                     values (     ?,   ?,   ?,   ?,   ?,   ?,   ?,   ?,   ?,  ?,     ?,         ?)
      on duplicate key update cat0=?, cat1=?, cat2=?
");                                                # ^^^ etc.

##</code><code>##

$db_update_cmd = $db_update_cmd."cat$cat=1,";

##</code><code>##

$db_update_cmd .= "cat$cat=1,";

##</code><code>##

if ( $preference =~ tr/0//) 

##</code><code>##

if ( $preference =~ /0/ )
# should be a more robust regexp to only capture '0', this is just to show the right operator