Prova detta
$db->setAttribute(PDO::MYSQL_ATTR_INIT_COMMAND, "SET NAMES 'utf8'");
$word = utf8_encode('pépite');
$sql = "INSERT INTO keyword(key_name) VALUES(?)";
$stmt = $db->prepare($sql);
$stmt->execute(array($word));
Prova detta
$db->setAttribute(PDO::MYSQL_ATTR_INIT_COMMAND, "SET NAMES 'utf8'");
$word = utf8_encode('pépite');
$sql = "INSERT INTO keyword(key_name) VALUES(?)";
$stmt = $db->prepare($sql);
$stmt->execute(array($word));