my $self->{_dbh} = $dbh;
$self->{_sth} = $sth;
bless $self, "xxx";
return $self;

##</code><code>##

my $self = {};
...
$self->{_dbh} = $dbh;
$self->{_sth} = $sth;
bless $self, "xxx";
return $self;