my ($user, $password, $dsn); ### Set these to run code
my $sql = "select * from tablename where id=?";

use strict;
use warnings;

use DBI;
my $dbh = DBI->connect($dsn, $user, $password, {RaiseError => 1});
my $sth = $dbh->prepare($sql);

my $result;
for(1..1000) {
  eval {
    $result = &simple_query;
  };
  if ($@) {
    print "Found error [$@]\n";
  } else {
    use Data::Dumper;
    warn Dumper($result);
  }
  sleep 1;
}

sub simple_query {
  $sth->execute(int(rand(7000)));
  my $ref = $sth->fetchrow_hashref or return;
  return $ref;
}
[download]

DBD::mysql::st fetchrow_hashref failed:
fetch() without execute() at ./db_connect line 31.
Found error DBD::mysql::st fetchrow_hashref failed:
fetch() without execute() at ./db_connect line 31.