This does not directly relate to your issue. However, whenever I have a query like that, I often prefer to build the sql statement instead of having a chain of placeholders that might or might not be balanced with the correct field.

To ensure better readability and quality assurance, I simply create an intermediate data structure that is transformed into the fields and values like so:

my @pairs = (
    name          => $name,
    country       => $country,
    language      => $language,
    union         => $union,
    title         => $title,
    email         => $email,
    cellphone     => $cellphone,
    landlinephone => $landlinephone,
    facebook      => $facebook,
    skype         => $skype,
    twitter       => $twitter,
    gender        => $gender,
    age           => $age,
    needshelp     => $needshelp,
);

my @fields = do {my $b = 0; grep {$b ^= 1} @pairs};
my @values = do {my $b = 1; grep {$b ^= 1} @pairs};

$sth = $dbh->prepare('INSERT INTO istanbul2011 SET ' . join ',', map {
+"$_=?"} @fields));
$sth->execute(@values) or die $dbh->errstr
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