Note: I have read all of the related PHP, UTF-8, character encoding articles that are usually suggested, but my question relates to data inserted before I applied such techniques. I am wishing to retrospectively fix all character encoding problems.

Now all connections are set as utf8 using PDO.

PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES utf8'

Unfortunately, a large amount of data was inserted that is of questionable encoding before I had implemented correct character encoding practices. As displayed by:

$sql = "SELECT name FROM data LIMIT 3";

foreach ($pdo->query($sql) as $row)
{
    $name = $row['name'];

    echo $name . "\n";
    echo utf8_encode($name) . "\n";
    echo utf8_decode($name) . "\n";
    echo htmlspecialchars($name, ENT_QUOTES, 'UTF-8') . "\n";
    echo htmlspecialchars(utf8_encode($name), ENT_QUOTES, 'UTF-8') . "\n";
    echo htmlspecialchars(utf8_decode($name), ENT_QUOTES, 'UTF-8') . "\n";
    echo '<hr/>';
}

Which produces:

Antonín Dvořák
AntonÃÆín DvoÃâ¦Ãâ¢ÃÆák
Anton??­n Dvo??????¡k
Antonín Dvořák
AntonÃÆín DvoÃâ¦Ãâ¢ÃÆák

----------
Ô±Ö€Õ¡Õ´ Ô½Õ¡Õ¹Õ¡Õ¿Ö€ÕµÕ¡Õ¶
ñÃâ¬Ã¡Ã´ ýáùáÿÃâ¬ÃµÃ¡Ã¶
????? ??????????
Ô±Ö€Õ¡Õ´ Ô½Õ¡Õ¹Õ¡Õ¿Ö€ÕµÕ¡Õ¶
ñÃâ¬Ã¡Ã´ ýáùáÿÃâ¬ÃµÃ¡Ã¶

----------
Tiësto
Tiësto
Tiësto
Tiësto
Tiësto
Tiësto
----------

When removing 'SET NAMES utf8' with PDO it produces the data:

Antonín DvoÅák
Antonín DvoÃÂák
Antonín Dvorák
Antonín DvoÅák
Antonín DvoÃÂák
Antonín Dvorák
----------
???? ?????????
Ô±ÖÕ¡Õ´ Ô½Õ¡Õ¹Õ¡Õ¿ÖÕµÕ¡Õ¶
???? ?????????
???? ?????????
Ô±ÖÕ¡Õ´ Ô½Õ¡Õ¹Õ¡Õ¿ÖÕµÕ¡Õ¶
???? ?????????
----------
Tiësto
Tiësto
Ti?sto
Tiësto
Tiësto

----------

And here is a dump of the database rows concerned:

DROP TABLE IF EXISTS `data`;
CREATE TABLE IF NOT EXISTS `data` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(80) NOT NULL,
  PRIMARY KEY (`id`),
  KEY `name` (`name`(10)),
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 AUTO_INCREMENT=0;

INSERT INTO `data` (`id`, `name`) VALUES (0, 'Antonín Dvořák'), (1, 'Արամ Խաչատրյան'), (2, 'Tiësto');

The 3rd and 6th lines of the 3rd row "Tiësto" are then correctly echoed. I'm just unsure what is the best way to correct encodings/detect the encodings of bad strings and correct, etc.