re-executing prepared statement leads to 'Modification of a read-only value attempted'

Hi,

While playing with the examples from the eg/ directory 
(DBD-mysql-3.0006_1) I took proc_example3.pl and
copied the $sth->execute and the subsequent do-block.
The second execution then leads to a
    Modification of a read-only value attempted
at the line with while (@row= $sth->fetchrow_array()). (The problem here 
is with $sth)

My environment: SLES9 with stock perl (5.8.3), Mysql 5.0.21, DBI 1.51, 
DBD::mysql 3.0006_1.

The test-script:

#!/usr/bin/perl

use DBI;

$DATABASE='test';
$HOST='localhost';
$PORT=3306; $USER='root';
$PASSWORD='';

$dbh = DBI->connect("DBI:mysql:$DATABASE:$HOST:$PORT",
                   "$USER", "$PASSWORD",
                 { PrintError => 0}) || die $DBI::errstr;


$dbh->trace(3, "./dbd.log");

$dbh->do("drop procedure if exists testproc") or print $DBI::errstr;

$dbh->do("create procedure testproc() deterministic
 begin
 declare a,b,c,d,e,f int;
 set a=1;
 set b=2;
 set c=3;
 set d=4;
 set e=5;
 set f=6;
 select a, b, c, d;
 select d, c, b, a;
 select b, a, c, d;
 select c, b, d, a;
 select a, d;
 select a, b, c, d, e, f;
 select f;
 end") or print $DBI::errstr;

$sth=$dbh->prepare('call testproc()') ||  die $DBI::err.": ".$DBI::errstr;

$sth->execute || die DBI::err.": ".$DBI::errstr; $rowset=0;
do {
  print "\nRowset ".++$i."\n---------------------------------------\n\n";
  foreach $colno (0..$sth->{NUM_OF_FIELDS}) {
    print $sth->{NAME}->[$colno]."\t";
  }
  print "\n";
  while (@row= $sth->fetchrow_array())  {
    foreach $field (0..$#row) {
      print $row[$field]."\t";
    }
    print "\n";
  }
} until (!$sth->more_results)
   ;

$sth->execute || die DBI::err.": ".$DBI::errstr; $rowset=0;
do {
  print "\nRowset ".++$i."\n---------------------------------------\n\n";
  foreach $colno (0..$sth->{NUM_OF_FIELDS}) {
    print $sth->{NAME}->[$colno]."\t";
  }
  print "\n";
  while (@row= $sth->fetchrow_array())  {
    foreach $field (0..$#row) {
      print $row[$field]."\t";
    }
    print "\n";
  }
} until (!$sth->more_results)
   ;


The result:

Rowset 1
---------------------------------------

a       b       c       d
1       2       3       4

Rowset 2
---------------------------------------

d       c       b       a
4       3       2       1

Rowset 3
---------------------------------------

b       a       c       d
2       1       3       4

Rowset 4
---------------------------------------

c       b       d       a
3       2       4       1

Rowset 5
---------------------------------------

a       d
1       4

Rowset 6
---------------------------------------

a       b       c       d       e
1       2       3       4       5       6

Rowset 7
---------------------------------------

f
6

Rowset 8
---------------------------------------

a       b       c       d
Modification of a read-only value attempted at ./tt.pl line 62.


Is this faulty behavior or am I using it the wrong way?

Thanks for any help,

Paul Lucassen

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