Active Record - CodeIgniter : multiple COUNT on 3 joined tables

Question

Working on a project with CodeIgniter and Active Record.

I face an issue with a query : I have 3 tables in my database which I would like not only to join but also to make countS on 2 of them. The tables are respectively linked with user_id, store_user_id, event_user_id fields

Table 1 : user user_id

Table 2 : store store_user_id

Table 3 : event event_user_id

What I am trying to do is to :

1 - Get all the data from user 2 - Count the number of stores with store_user_id = user_id (it may be 0) 3 - Count the number of events with event_user_id = user_id (it may be 0)

I have done this in my function :

    $this->db->select('*');
    $this->db->select('COUNT(s.store_user_id) as total_store', FALSE);
    $this->db->select('COUNT(e.event_user_id) as total_event', FALSE);
    $this->db->from('user u');
    $this->db->join('store s', 's.store_user_id = u.user_id', 'left'); // this joins the user table to store table
    $this->db->join('event e', 'e.event_user_id = u.user_id', 'left'); // this joins the user table to event table  
    $this->db->group_by('u.user_id');

    $q = $this->db->get();
    if ($q->num_rows()>0){
        foreach ($q->result() as $rows) {       
            $data[] = $rows;
        }

        return $data;
    }

The trouble is that when I display total_store and total_event in my view, the results are the same and I think figures are multiplied between them..

For example : For an user I have 3 events en 4 stores, the results displayed will be total_event = total_store = 12 ...

I don't understand why and it makes me crazy for hours!! Moreover, when I make only one count, the result is correct..

Any idea??

Many thanks in advance :)

Answer 1

Lastly I have implemented this basic SQL query :

$this->db->query('SELECT 
                u.*,
                x.total_store,
                y.total_event
            FROM 
            user u

            LEFT OUTER JOIN (SELECT s.store_user_id, COUNT(s.store_user_id) AS total_store
                FROM store s

                GROUP BY s.store_user_id) x ON x.store_user_id = u.user_id

            LEFT OUTER JOIN (SELECT e.event_user_id, COUNT(e.event_user_id) AS total_event  

            FROM event e

                GROUP BY e.event_user_id) y ON y.event_user_id = u.user_id
        ');

Hope it will helps others

Answer 2

When you count() you're counting the number of rows, not the number of distinct values in the result set. You're right that the number is being multiplied: there's a row in your resultset for each user-store-event combination.