Why is $sth->rows() uninitialized?

Thanks to the suggestions of Greg and others, I was able to use $sth-rows() to determine if a record was present or not in my table. Thanks, Greg. The section of code I used successfully is:
      $kwsth->execute($_) or warn "Problem with execute: $DBI::errstr\n";
      
      if ($kwsth->rows() == 0) { 
         print "Keyword $_ not found " if $debug; 
         $inskwsth->execute($_);
         $keywordid = $dbh->{'mysql_insertid'};
         print "NEW id = $keywordid\n" if $debug;
   
      } else { # If the keyword doesn't already exist in the table, else...
      
         $keywordid = $kwsth->fetchrow_array or warn "Problem with fetch: $DBI::errstr\n";
         print "Keyword ID: $keywordid\n" if $debug;
      } # else if the keyword DOES exist in the table already


Now I'm trying to apply this to another program in an almost identical fashion, and don't understand why I'm getting an error. The section of code is:
   my $sth = $dbh->prepare("SELECT baseitemid FROM langversions WHERE baseitemid =? AND langid=?");
   $sth->execute($baseitemid, $langid);
   
   if ($sth->rows() == 0) { #THIS is line 70
      print STDERR "Duplicate item found at line $ln: $_\n";
   } else {
      my $sth = $dbh->prepare("INSERT INTO langversions (baseitemid, langid, title, cost, available) VALUES (?, ?, ?, ?, ?)" ) or die "Can't prepare statement: $DBI::errstr";
      $sth->execute($baseitemid, $langid, $title, $cost, $available)
         or die "Can't execute statement: $DBI::errstr";
   } # else if there was no duplicate item

When I execute this with trace(2) set, I get this section of the output:
    <- prepare= DBI::st=HASH(0x828b1f0) at loadInventory.pl line 67
    -> execute for DBD::mysql::st (DBI::st=HASH(0x828b1f0)~0x81e27e0 '1' '1')
    -> dbd_st_execute for 0828b220
      Binding parameters: SELECT baseitemid FROM langversions WHERE baseitemid ='1' AND langid='1'
    <- dbd_st_execute 0 rows
    <- execute= '0E0' at loadInventory.pl line 68
    -> rows for DBD::mysql::st (DBI::st=HASH(0x828b1f0)~0x81e27e0)
    <- rows= '0' at loadInventory.pl line 70
Use of uninitialized value in concatenation (.) or string at ./loadInventory.pl line 70.
Duplicate item found at line 1: 

The last line is my STDERR output. The previous line is an error message. The trace() output seems to show rows() being set to '0' at line 70,  which is "if ($sth->rows() == 0) {".

I don't understand perl says $sth->rows() isn't initialized, when it seems to be set to zero, and why this system isn't working in this program, but seems to work fine in my other one.

Thanks for any light you can shed on this problem.

-Kevin

-- 
MySQL Perl Mailing List
For list archives: http://lists.mysql.com/perl
To unsubscribe:    http://lists.mysql.com/[email protected]