generate JSON with rows grouped by a specific column

MySQL -> JSON by Column

<?php
mysql_connect("localhost", "root", "");
mysql_select_db("coins");
$result = mysql_query("select * from coins");

$list = array();
while ($r = mysql_fetch_object($result)) {
	$list[$r->society][] = $r->ID;
}
print_r(json_encode($list));