my @fields = sort keys %prophash;
my $sql = 'INSERT INTO maintable ('.join(',',@fields)
    .') values ('.join(',',('?')x(scalar @fields)).')';
my $sth = $dbh->prepare($sql)
    or die "Can't prepare statement\n\n$sql\n\n$dbh->errstr()";
$sth->execute(@prophash{@fields})
    or die "Can't execute statement : $db->errstr()";