Online PHP editor | refs for vHUWR

<?php $data = [ ['DEPARTMENT_ID_FK' => '001', 'EMAIL_ADDRESS' => 'a@example.com'], ['DEPARTMENT_ID_FK' => '002', 'EMAIL_ADDRESS' => 'a@example.com'], ['DEPARTMENT_ID_FK' => '001', 'EMAIL_ADDRESS' => 'c@example.com'], ]; $agg = []; foreach ($data as $dData) { $dep = $dData['DEPARTMENT_ID_FK']; $email = $dData['EMAIL_ADDRESS']; if (isset($agg[$dep])) { $agg[$dep][] = $email; continue; } $agg[$dep] = [$email]; } $result = []; foreach ($agg as $dep => $emails) { $result[] = [ 'DEPARTMENT_ID_FK' => $dep, 'EMAIL_ADDRESS' => implode(',', $emails), ]; } print_r($result);