Classe model

model.php

<?php

function search($date = null, $departure = null, $arrival = null)
  {
    if ($departure == null || $arrival == null)
      return null;
    if ($date != null) {
	$day_time = strtotime($date);
	$day_time_end = $day_time + 86400;
	$sql = 'SELECT * FROM `ride` as r, `user` as u
	WHERE r.`user_id` = u.`id`
	AND r.`towndeparture` LIKE "%'.urldecode($departure).'%"
	AND r.`townarrival` LIKE "%'.urldecode($arrival).'%"
	AND r.`timestamp` >= "'.$day_time.'"
	GROUP BY `id_ride`';
    }
    else
      $sql = 'SELECT * FROM `ride` as r, `user` as u
	WHERE r.`user_id` = u.`id`
	AND  r.`towndeparture` LIKE "%'.urldecode($departure).'%"
	AND r.`townarrival` LIKE "%'.urldecode($arrival).'%"
	AND r.`timestamp` > NOW() + 3600
	GROUP BY  `id_ride` ;';
    $query = $this->db->query($sql);
    if ($query->num_rows() > 1) {
      $result = array();
      foreach ($query->result() as $row)
	$result[] = $row;
      return $result;
    }
    if ($query->num_rows() == 1)
      return array($query->row());
    return null;
  }

Refactoring

Voila comment je l'aurais fais moi:

<?php
function search($departure, $arrival, $date = null)
{
    if (!$date) {
        $dayTime = time() + 3600;
        } else {
        $dayTime = strtotime($date);
    }

    $sql = 'SELECT * FROM `ride` as r, `user` as u
        WHERE r.`user_id` = u.`id`
        AND r.`towndeparture` LIKE "%:departure%"
        AND r.`townarrival` LIKE "%:arrival%"
        AND r.`timestamp` >= ":dayTime"
        GROUP BY `id_ride`';

    $params = ['departure' => $departure, 'arrival' => $arrival, 'dayTime' => $dayTime];
    $preparedQuery = $this->db->prepareQuery($sql, $params); // pseudo code
    $query = $this->db->query($preparedQuery);

    $result = [];
    foreach ($query->result() as $row) {
        $result[] = $row;
    }
    return $result;
}