Hmmm ... well I would think you're either not connecting to the same server (probably not) or you're not in the database you think your in. At a minimum, your sql could be failing but you're not checking the status of your execute. I would put some error checking in place or at least set RaiseError.

my $dbh = DBI->connect( 
  "dbi:Oracle:host=$host;port=$port;sid=$sid",
  $user, $passwd, {RaiseError => 1}
);
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