sub connect
{
my $dsn = "DBI:mysql:host=$host_name";
my %conn_attrs = (PrintError => 0, RaiseError => 1, AutoCommit => 1);

  $dsn .= ";database=$db_name" if defined $db_name;
  $dsn .= ";mysql_socket=$socket_file" if defined $socket_file;
  $dsn .= ";port=$port_num" if defined $port_num;

  return (DBI->connect ($dsn, $user_name, $password, \%conn_attrs ));
}