写得好纠结，目前不知道哪里有问题，还在研究。。

package TDmodule;use DBI;sub new{  $self={};  $self->{username}=undef;  $self->{password}=undef;  $self->{host}=undef;  $self->{database}=undef;  $self->{connect_db}=[];  $self->{select_db}=undef;  bless $self;  return $self;}sub username{  my $self=shift;  if(@_){    $self->{username}=shift;  }  return $self->{username};}sub password{  my $self=shift;  if(@_){    $self->{password}=shift;  }  return $self->{password};}sub host{  my $self=shift;  if(@_){    $self->{host}=shift;  }  return $self->{host};}sub database{  my $self=shift;  if(@_){    $self->{database}=shift;  }  return $self->{database};}sub connect_db{  my $self=shift;  @{
    $self->{connect_db}}=DBI->connect("DBI:mysql:database=$self->{database};host=$self->{host}","$self->{username}","$self->{password}") or die "No:$!\n";  @{
    $self->{connect_db}}->prepare("select * from old_papar");  @{
    $self->{connect_db}}->execute();  return @{
   $self->{connect_db}};}sub select_db{  my $self=shift;  if(@_){      $db=@{
   $self->{connect_db}};      my $select=$db->prepare(@_);      $select->execute();      $self{select_db}=$select->fetchrow_hashref();      @{
    $self->{connect_db}}->disconnect;  }  return $self{select_db};}1;