用join codeigniter进行求和查询

Question

I have 2 tables. One with a list of clients and another with a list of data. I am trying to create a table in my view that lists the client name along with the sum of a column(job_total) in the data table. I am able to write a query that works fine in most situations. The problem is, if I have not yet created a record in the data table I need to still display the client name with a balance of zero on my table in my view. Need some direction on how to handle this. I was thinking I need to query my list of clients and loop through that query just not sure how to do it.

I want my view to look like below:

+-------------+---------+
    | Client Name | Balance |
    +-------------+---------+
    | xxx         | $75.00  |
    | xxx         | $100.00 |
    | xxx         | $0.00   |
    +-------------+---------+

Here is a rough layout of the two tables in my database:

cj_clients
    +----+-------------+
    | id | client name |
    +----+-------------+
    | 1  | client1     |
    | 2  | client2     |
    | x  | xxx         |
    +----+-------------+

cj_data
    +----+-----------+-----------+
    | id | client_id | job_total |
    +----+-----------+-----------+
    |  1 |         1 |      5.00 |
    |  2 |         1 |     10.00 |
    |  3 |         1 |     15.00 |
    +----+-----------+-----------+

The below code returns the desired results except when no entries have yet been made to the cj_data table. Not sure how to still get the client in the table view with a balance of $0.

$this->db->select('client_name,client_id, sum(job_total) AS balance')
     ->from('cj_data')
     ->join('cj_clients','cj_data.client_id = cj_clients.id')
         ->group_by('client_name');

return $this->db->get()->result();

Answer 1

You need to give left join

$this->db->select('client_name,client_id, IFNULL(sum(job_total),0) AS balance')
     ->from('cj_data')
     ->join('cj_clients','cj_data.client_id = cj_clients.id',"left") // here
         ->group_by('client_name');

return $this->db->get()->result();

I wrote IFNULL condition if record not found or it will show all data for all clients in cj_clients

Note: the Default behaviour of CodeIgniter is it will add inner join if join not specified