Joining equal values​​, that were returned from a database

group-by-in-zend-db.php

/**
 * The following code builds this query: 
 * SELECT `amount`
 *      , GROUP_CONCAT(`Name` SEPARATOR ', ') AS `name`
 * FROM `table` 
 * GROUP BY `amount` 
 * ORDER BY `amount` DESC
 * LIMIT 0, 3
 */
public function getSome()
{
    $select = $this->tableGateway->getSql()->select();
    $select->columns([
        'amount',
        'name' => new \Zend\Db\Sql\Expression("GROUP_CONCAT(Name SEPARATOR ', ')")
    ])
        ->order('amount DESC')
        ->group('amount')
        ->limit(3);

    return $this->tableGateway->selectWith($select);
}