use strict;
use warnings;
use Data::Dumper;
use Util_DB;

main();

sub main {
  my $db   = Util_DB->new({
                           'dsn'      => 'myapp',
                           'user'     => 'root',
                           'password' => ''
                         });

  $db->main::select_class_a();
  print "----", "\n";
  $db->main::select_class_a('bb');
}
 
sub select_class_a {
  my $dbh  = shift->{'dbh'};
  my $name = shift;
 
  my $sql;
  my $sth;
  if( !defined $name ){
    $sql = q{ 
              SELECT
                *
              FROM
                class_a
            };
    $sth   = $dbh->prepare($sql); 
    $sth->execute();
  }else{
    $sql = q{ 
              SELECT
                *
              FROM
                class_a
              WHERE
                name = ?
            };
    $sth   = $dbh->prepare($sql); 
    $sth->execute($name);
  }


  while(my $row = $sth->fetchrow_hashref()){
    print Dumper $row;
  }
}

use strict;
use warnings;
use DBI;

package Util_DB;

sub new {
  my $self  = shift;
  my $class = ref($self) || $self;

  my $c      = shift;

  my $dbh = DBI->connect(
                         'DBI:mysql:database=' . $c->{'dsn'},
                         $c->{'user'},
                         $c->{'password'},
                         {'PrintError'=>1, 'RaiseError'=>1}
                        );

  return bless {'dbh' => $dbh}, $class;
}

1;