将mysql查询转换为CodeIgniter $ query-> row

Question

How to convert this query to CodeIgniter?

$date = '28-05-2019';
$time_start = '10:00';
$time_end = '19:00';

select courtrooms.* from courtrooms
left join reservations 
on courtrooms.id = reservations.courtroom_id
and reservations.date = '$date' and reservations.time_start < '$time_start' and reservations.time_end > '$time_end'
where reservations.id is null

Answer 1

There are actually several ways to write queries in Codeigniter, the following syntaxis is the most understandable from my point of view if you are just starting to write queries using this framework.

Please see Query Builder Class

$this->db->select('*');
$this->db->from('courtrooms');
$this->db->join('reservations','courtrooms.id = reservations.courtroom_id','left');
$this->db->where('reservations.id IS NULL', null, false);
$this->db->where('reservations.date', $date); 
$this->db->where('reservations.time_start<', $time_start);
$this->db->where('reservations.time_end>', $time_end);
$query = $this->db->get();

$query = $query->result();

The above code is the same than this one:

$query = $this->db->join('reservations','courtrooms.id = reservations.courtroom_id','left')
                  ->where('reservations.id IS NULL', null, false)
                  ->where('reservations.date', $date)
                  ->where('reservations.time_start<', $time_start)
                  ->where('reservations.time_end>', $time_end)
                  ->get('courtrooms');
$query = $query->result();