/*

$check = $this->check_before_send();

if ($check) {
//  что-то делаем
}

*/


 public function check_before_send() {

        $sql = "SELECT * FROM signals_before_send WHERE symbol =  '" . $this->symbol . "' AND signal_from = '" . $this->signal_from . "' AND time_insert < '" . time() - (int)20 . "'";

        $check_result = $this->db->query($sql);

        if ($check_result->num_rows > 0) {

            return false;

        } else {

            $sql = "INSERT INTO `signals_before_send`(
              `symbol`,
              `signal_from`,
              `time_insert`
            ) VALUES('" .
              implode("','", [
                $this->symbol,
                $this->signal_from,
                time()
              ])
            . "')";

            $this->db->query($sql);
            return true;
        }

    }