# some standard DBI code doing an INSERT here..
my $dbh = ...;
my $sth = $dbh->prepare('...');
$sth->execute(@values);

my $seq = 'SOME_SEQUENCE_NAME';
my $sth = $dbh->prepare("SELECT currval('$seq')");
$sth->execute() or die $dbh->errstr;
if (my @row = $sth->fetchrow_array) {
  return $row[0];
}