gistfile1.php

<?php
$result = $db->query('SELECT 
wp1.meta_value AS first_name, 
wp2.meta_value AS last_name
FROM 
wp_usermeta wp1
INNER JOIN
wp_usermeta wp2
ON ( wp1.user_id = wp2.user_id )
WHERE 
wp1.user_id = 19
AND wp1.meta_key = "first_name"
AND wp2.meta_key = "last_name"');
while ($row = $result->fetch_array()) {
	echo $row['first_name'] . PHP_EOL;
	echo $row['last_name'] . PHP_EOL;
}
?>