mysql Join showing wrong result PHP - php

Question

I have following three tables:
taxi:
id shopid taxiId status
1 20 1 1
2 20 2 1
3 20 3 2
4 20 4 1
5 21 1 1
...
preBooking:
id shopid taxiId status
1 20 1 booked
2 20 3 booked
usrBooking:
id shopid taxiId status
1 20 2 booked
2 20 4 booked
Now I want to get all records from taxi table ( for example shop id=20), and matching record of preBooking and usrBooking table.
For example I want to get records like this (if i pass shop id 20 in parameter)
id shopid taxiId preBookingstatus usrBookingstatus
1 20 1 Booked Null
2 20 2 Null Booked
3 20 3 Booked Null
4 20 4 Null Booked
I tried with following code but not working correctly,showing wrong results
$shopid="20";
$this->db->select('t.taxiId,ub.status as usrBookingstatus ,pb.status as preBookingstatus ');
$this->db->from('taxi t');
$this->db->join('usrBooking ub', 'ub.taxiId=t.taxiId','LEFT OUTER');
$this->db->join('preBooking pb', 'pb.taxiId=t.taxiId','LEFT OUTER');
$this->db->where('t.shopid', $shopid);
$this->db->order_by('t.taxiId', 'ASC');

Answer 1

First I am unsure what is this:
$this->db->where('c.salon_id', $shopid);
There is no table "c" in the FROM of the query and "salon_id" is not mentioned in the example data above. This makes the query invalid and you can't run it. Maybe this is the issue. Probably you should change it to:
$this->db->where('t.shopid', $shopid);
Also you are missing some columns in the SELECT. The full query should be:
SELECT t.id, t.shopid, t.taxiId, pb.status as preBookingstatus, ub.status as usrBookingstatus
FROM taxi t
LEFT JOIN usrBooking ub ON ub.taxiId=t.taxiId
LEFT JOIN preBooking pb ON pb.taxiId=t.taxiId
WHERE t.shopid = 20
ORDER BY t.taxiId ASC;
Or with your PHP code:
$shopid="20";
$this->db->select('t.id, t.shopid, t.taxiId, pb.status as preBookingstatus, ub.status as usrBookingstatus');
$this->db->from('taxi t');
$this->db->join('usrBooking ub', 'ub.taxiId=t.taxiId','LEFT OUTER');
$this->db->join('preBooking pb', 'pb.taxiId=t.taxiId','LEFT OUTER');
$this->db->where('t.shopid', $shopid);
$this->db->order_by('t.taxiId', 'ASC');

Answer 2

It seems as if your select statement is missing a few columns. Change
$this->db->select('t.taxiId,ub.status as usrBookingstatus ,pb.status as preBookingstatus ');
to
$shopid=20;
$this->db->select('t.id, t.shopid, t.taxiId,pb.status as preBookingstatus , ub.status as usrBookingstatus ');
$this->db->from('taxi as t');
$this->db->join('usrBooking as ub', 't.taxiId=ub.taxiId','LEFT');
$this->db->join('preBooking as pb', 't.taxiId=pb.taxiId','LEFT');
$this->db->where('t.shopid', $shopid);
$this->db->order_by('t.taxiId', 'ASC');