my $hash = $dbconn->selectall_hashref($sql_statement);

##</code><code>##

  my $sth  = $dbconn->prepare($sql_statement);
      .   .   .   .   .   .   .
  my $hash = $dbconn->selectall_hashref($sth);

##</code><code>##

  {
    local $dbconn->{RaiseError} = 1;
    my $hash = $dbconn->selectall_hashref($sql_statement);
      .   .   .   .   .   .   .
  }