Thank you hippo for pointing this out, however, the snippet I've inserted into my recent post, is the piece of code, that was removed and replaced by the code, that roboticus kindly suggested to me in his post.

So instead of:

my $SQL = "INSERT INTO $table VALUES (" 
        . join(",", map { "?" } $csv->fields)
        . ")";
$prep = $db->prepare($SQL) or die "...";
while (my $row = $csv->getline($fh)) {
    $prep->execute($csv->fields);
}
[download]

I used:

my $SQL = "INSERT INTO $table VALUES (" 
        . join(",", map { "?" } $csv->fields)
        . ")";
$prep = $db->prepare($SQL) or die "Cannot prepare database";
while (my $row = $csv->getline($fh)) {
    $prep->execute($csv->fields);
}
[download]

It does not change the fact, that I still struggle with this new error:

Sorry, I misread your post. Your placeholders there look OK at first pass.

So, for starters I would use @$row as the argument to execute and then I would compare the number of fields in $row with the number of fields in your database for $table and see where the mismatch occurs. HTH.