DBD::mysql::st fetchrow_hashref failed: fetch() without execute() at

Digioso has asked for the wisdom of the Perl Monks concerning the following question:

Hi Monks, I am having some trouble with a MySQL statement, or rather the fetchrow_hashref to get the data. It always returns the error message "DBD::mysql::st fetchrow_hashref failed: fetch() without execute() at", but nevertheless the results are completely fine and as expected. I have no idea what is causing this error.
$error returns 1

My code:

my $dbh = DBI->connect("DBI:mysql:$db:$host", $user, $pw) || die;

my $sql;
my $sth;

if($ENV{'REQUEST_METHOD'} eq 'GET')
{
    my $daten;
    $daten = $ENV{'QUERY_STRING'};
    my @formularfelder = split(/&/, $daten);
    my @formular = ();
    my $i=0;
    foreach my $feld (@formularfelder)  
    {
        (my $name, my $value) = split(/=/, $feld);   
        $value =~ tr/+/ /;
        $value =~ s/%([a-fA-F0-9][a-fA-F0-9])/pack("C", hex($1))/eg;
        $value =~ s/<!--(.|\n)*-->//g;      
        $formular[$i] = $cgi->escapeHTML($name);
        $i++;
        $formular[$i] = $cgi->escapeHTML($value); 
        $i++;
    }
    if(!defined $formular[0] || $formular[0] ne "dl" || ! defined $for
+mular[1] || $formular[1] !~ /^\d+$/)
    {
        Navi::print_navi(": Nice try... :");
        print qq{<div id="category">[ NICE TRY ]</div>};
        print "<b>Nice try...</b>";
    }
    else
    {
        $sql = qq{select p.category as category, p.titel as titel, p.b
+eschreibung as beschreibung , c.werbung as werbung from movie_project
+s as p join movie_categories as c on c.id = p.category WHERE p.id = ?
+};
        
        $sth = $dbh->prepare($sql) or die "Error: $DBI::errstr";
        my $error = $sth->execute($formular[1]) or die "Error: $DBI::e
+rrstr";
        print "$error\n";
        
        while (my $ergebnis = $sth->fetchrow_hashref())
        {
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Comment on DBD::mysql::st fetchrow_hashref failed: fetch() without execute() at Download Code

Replies are listed 'Best First'.
Re: DBD::mysql::st fetchrow_hashref failed: fetch() without execute() at by choroba (Cardinal) on Oct 29, 2024 at 13:49 UTC
Have you search PerlMonks for similar questions? This one seems relevant and might even contain a solution: fetchrow_hashref failed problem. `map{substr$_->[0],$_->[1]\|\|0,1}[\\|\|{},3],[[]],[ref qr-1,-,-1],[{}],[sub{}^ARGV,3]`	[reply] [d/l]
Re: DBD::mysql::st fetchrow_hashref failed: fetch() without execute() at by cavac (Prior) on Oct 30, 2024 at 08:46 UTC
Why do you use $DBI::errstr? Oh, i see, the docs for DBD::mysql mix it up. Try looking at $dbh->errstr (as seen in the examples at the top of the documentation) instead to see if there's a difference. Did you try the statement directly in the mysql client? make sure no other transactions are currently locking the table? try $dbh->ping() as a basic test to see if your connection to the database actually works? check what $dbh->errstr shows directly after the DBI->connect() call? re-install/recompile DBD::mysql to make sure you are using the correct version of the C library? check the database logfiles? Is there anything in them that might hint at an error? PerlMonks XP is useless? Not anymore: XPD - Do more with your PerlMonks XP Also check out my sisters artwork and my weekly webcomics	[reply]
Re^2: DBD::mysql::st fetchrow_hashref failed: fetch() without execute() at by Digioso (Sexton) on Oct 30, 2024 at 13:22 UTC
Edit: Dang... I found the issue. I've reused $sth within the while loop... Thanks a lot for your help, everyone!	[reply]
Re: DBD::mysql::st fetchrow_hashref failed: fetch() without execute() at by LanX (Saint) on Oct 29, 2024 at 13:55 UTC
Please ignore, English cat was running over my keyboard and confusing me. ~~I don't think execute returns an error but a result object.~~ ~~It's on this object you call fetch-methods not on the sth statement handle.~~ ~~Edit~~ ~~Yes see execute of DBI~~ Cheers Rolf _{(addicted to the Perl Programming Language :) see Wikisyntax for the Monastery}	[reply]
Re^2: DBD::mysql::st fetchrow_hashref failed: fetch() without execute() at by ysth (Canon) on Oct 29, 2024 at 14:00 UTC
No, you use the statement handle. Reread the doc you linked. -- A math joke: r = \| \|csc(θ)\|+\|sec(θ)\| \|-\| \|csc(θ)\|-\|sec(θ)\| \|	[reply]
Re^3: DBD::mysql::st fetchrow_hashref failed: fetch() without execute() at by LanX (Saint) on Oct 29, 2024 at 14:02 UTC
Already updated Cheers Rolf _{(addicted to the Perl Programming Language :) see Wikisyntax for the Monastery}	[reply]
Re^2: DBD::mysql::st fetchrow_hashref failed: fetch() without execute() at by Digioso (Sexton) on Oct 29, 2024 at 14:05 UTC
Thanks! I've already searched here and in other forums, but couldn't find a solution. But I've fixed it now by simply removing the loop. The select statement can only return one row. So instead of the loop I am simply writing that into a variable. my $ergebnis = $sth->fetchrow_hashref(); Still I don't understand why using this in a while loop causes an error. oO	[reply]
Re^3: DBD::mysql::st fetchrow_hashref failed: fetch() without execute() at (Updates:2) by LanX (Saint) on Oct 29, 2024 at 14:35 UTC
My guess is it's called again after the successful call, but I can't test at the moment. The undef shouldn't allow this. I normally only use `->fetchall_hashref` Update Did you show us how you checked on this error after the fetch? Or do you auto-raise them with RaiseError of DBI ? Update In general it's better to supply a SSCCE to reproduce the issue instead of all this less relevant CGI Code Cheers Rolf _{(addicted to the Perl Programming Language :) see Wikisyntax for the Monastery}	[reply] [d/l]
Re^4: DBD::mysql::st fetchrow_hashref failed: fetch() without execute() at (Updates:2) by cavac (Prior) on Oct 30, 2024 at 09:14 UTC

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