# 1

# (I don't know which module you're using for your $query->Dump expression,
#  so I'll simply be using the old school CGI.pm here)

use CGI 'param';
use DBI;
my $dbh = DBI->connect(...) or die ...;
my $id = param 'id';

# Hit the database with an UPDATE for every parameter
for my $p (param) {
    next if $p eq 'id';
    my $sql = sprintf("UPDATE mytable SET %s = ? WHERE id = ?", $p)
    $dbh->do($sql, undef, param($p), $id);
}

##</code><code>##

# 2

# (again, just CGI.pm)

use CGI 'param';
use DBI;
my $dbh = DBI->connect(...) or die ...;

my $id = param 'id';
my %update = map { $_ ne 'id' ? ($_ => param($_)) : () } param;
my @bind = ();
# First, build one large UDPATE statement
# and collect the bind values while we're at it
my $sql = "UPDATE mytable SET " .            # Doing this from the top of my head,
          join(", ",                         # untested, but it should get the 
            grep defined, map {              # idea across
                if ($_ ne 'id') {
                    push @bind, param($_);
                    sprintf "%s = ?", $_
                }
                else { undef }
            } param
          )
;

# And then hit the database with that UPDATE statement just once.
$dbh->do($sql, undef, bind);