my $sth = $dbh->prepare_cached("INSERT INTO bla (colname1, colname2) VALUES (?, ?) RETURNING bla_id")
    or croak($dbh->errstr);
$sth->execute($val1, $val2) or croak($dbh->errstr);
my $line = $sth->fetchrow_hashref;
$sth->finish;
$dbh->commit;

print "Inserted data with new primary key ", $line->{bla_id}, "\n";