in reply to DBI::fetchall_arrayref() error

You need to add an explicit row count check before your inner for loop to prevent infinite loop:

while (my $rows = $sth->fetchall_arrayref(undef, 3)) {
          # ^ this condition is always true
          #   why? because when there is nothing to fetch,
          #   $rows is reference to an empty array, not undef

  last if ($#$rows < 0); # break out of infinite loop

  for (@$rows) {
     ...

[download]

I am using version 1.39 of DBI and I could not repeat the same error, fetch without execute, as you have indicated.

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Re: Re: DBI::fetchall_arrayref() error
by pg (Canon) on Jan 12, 2004 at 01:55 UTC

    No.

    I tried this piece of code, it fails with the same error:

    use DBI;
use Data::Dumper;
use strict;

my $dbh = DBI->connect('dbi:ODBC:TestingDB',"","",{RaiseError => 1, Au
+toCommit=>1}) || die "failed";
my $sth = $dbh->prepare("select cof_name, price from coffees") or die;
$sth->execute or die;
while (my $rows = $sth->fetchall_arrayref([0,1]), 3) {
    last if ($#$rows < 0);
}
$dbh->disconnect();

    [download]

    And this does not explain why it works, if you change [0] to undef. Even if what you said is right, should not fetchall_arrayref gives user the same interface, with undef and [0].

[reply]
[d/l]
[select]
      Hi pg, I used the following to do the test earlier:
      #!C:/Perl/bin/perl
use strict;
use DBI;
use DBD::Sybase;
use Data::Dumper;

my $dbh = DBI->connect("dbi:Sybase:server=SERVER;database=DATABASE",  
+                          "USER","PASSWORD")
    or die "Can not connect to database!";

my $sth = $dbh->prepare( qq{ select amount from trades_gdw_total });

$sth->execute();

while (my $rows = $sth->fetchall_arrayref([0], 3)) {
  last if ($#$rows <= 0);
  for (@$rows) {
    print "got @$_\n";
  }
  print "---\n";
}

      [download]

      And I got the desired behaviour, with no errors reported. I am using DBI version 1.39, with DBD::Sybase, by the way.

      I studied the source code of DBI, and extracted the following code concerning the behaviour of fetchall_arrayref:
        # we copy the array here because fetch (currently) always
  # returns the same array ref. XXX

  if ($slice && @$slice) {
    
    # if called with [0]

    $max_rows = -1 unless defined $max_rows;
    push @rows, [ @{$row}[ @$slice] ]
      while($max_rows-- and $row = $sth->fetch);
  }
  elsif (defined $max_rows) {

    # if called with undef

    $max_rows = -1 unless defined $max_rows;
    push @rows, [ @$row ]
      while($max_rows-- and $row = $sth->fetch);
  }
  else {
    push @rows, [ @$row ] while($row = $sth->fetch);
  }

      [download]

      And everything points to fetch.

[reply]
[d/l]
[select]

        Base on my conversation with Roger, both of us suspect this problem might be DBD dependent (or platform dependent?).

        Sounds like fetchall_arrayref() does not handle boundary nicely all the time.

        Although I didn't reply dbwiz, with the combination of my environment, his solution also failed.

[reply]

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