SELECT `p`.*
FROM `pupils` AS `p`
JOIN `pupils_cities` AS `pc` ON `pc`.`pupil_id` = `p`.`id`
JOIN (
SELECT `city_id`
FROM `pupils_cities`
GROUP BY `city_id`
ORDER BY COUNT(*) DESC
LIMIT 1
) AS `cnt` ON `cnt`.`city_id` = `pc`.`city_id`
<?php
define("URL_GET_USER",'https://api.vk.com/method/users.get');
$uid = "315131";
$query2 = "?user_ids=".$uid;
$kur = curl_init();
curl_setopt($kur, CURLOPT_URL, URL_GET_USER.$query2);
curl_setopt($kur, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($kur, CURLOPT_SSL_VERIFYHOST, false);
curl_setopt($kur, CURLOPT_RETURNTRANSFER, TRUE);
$result2 = curl_exec($kur);
curl_close($kur);
var_dump($result2);
?>
string(101) "{"response":[{"uid":315131,"first_name":"Дарья","last_name":"Воеводкина","hidden":1}]}"