public function deleteMessage(Request $r) {
Message::find($r->message_id)->delete();
$mes = DB::select("SELECT
d.id FROM dialogs d LEFT JOIN messages m ON LEAST(d.user_1, d.user_2) = LEAST(m.sender_id, m.receiver_id) AND GREATEST(d.user_1, d.user_2) = GREATEST(m.sender_id, m.receiver_id) WHERE m.dialog_id IS NULL");
if($mes){
$ids_to_delete = implode(', ', array_column($mes, 'id'));
$del = DB::delete("DELETE FROM dialogs WHERE id IN ($ids_to_delete)");
}
}