Are you really trying to capture the return value of $sth->fetchrow_array() in a scalar? Your comments imply that you're seeing data on STDOUT from the first print $fetchdata;, but I don't see how it could be the data you wanted. The DBI docs suggest:

   while ( @row = $sth->fetchrow_array ) {
      print "@row\n";
   }
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That said, it seems to me that you'd likely run into trouble if the return value were ever an empty string ("") or something else that evaluates to FALSE.