在codeigniter中使用一對多關系連接三個表

Question

我在codeigniter做一個項目。我想加入三個表

客戶（id，name，email，adminId，campaignId，dateAdded，is_deleted）

廣告系列（ID，名稱，adminId）和

訂單（id，name，cost，dateAdded，clientId）。

從這些表中我想選擇（在兩個日期之間）添加的客戶數量，活動名稱和客戶的總訂單成本。當我加入兩個表（客戶和活動）時，它返回正確的結果。

我使用的查詢是

$this->db->select('clients.id AS my_client,
    clients.name AS client_name,
    campaign.name AS campaign_name,
    DATE(clients.dateAdded) as client_date,
    COUNT(clients.id) AS num_rows');

$this->db->from('clients');
$this->db->where('clients.adminId', $adminId);
$this->db->where('DATE(clients.dateAdded) >=', $from_date);
$this->db->where('DATE(clients.dateAdded) <=', $to_date);
$this->db->join('campaign', 'campaign.id = clients.campaignId', 'left');
$this->db->group_by('campaign_name');
$query = $this->db->get();
return $query->result();

但當我加入三個表（客戶，活動，訂單）時，它沒有返回正確的結果。客戶和訂單之間的關系是一對多的。如果一個客戶可以有多個訂單。所以它不會給出正確的總值在兩個日期之間添加的客戶端數。我用來連接三個表的連接查詢是

$this->db->select('clients.id AS my_client,
    clients.name AS client_name,
    campaign.name AS campaign_name,
    DATE(clients.dateAdded) AS client_date,
    SUM(order.cost) AS order_cost,
    COUNT(clients.id) AS num_rows');

$this->db->from('clients');
$this->db->where('clients.adminId', $adminId);
$this->db->where('clients.is_deleted', 0);
$this->db->where('DATE(clients.dateAdded) >=', $from_date);
$this->db->where('DATE(clients.dateAdded) <=', $to_date);
$this->db->join('campaign', 'campaign.id = clients.campaignId', 'left');
$this->db->join('order', 'order.clientId = clients.id', 'left');
$this->db->group_by('campaign_name');
$query = $this->db->get();
return $query->result();

任何人都可以有一些想法這樣做。謝謝你提前

Answer 1

我通過計算不同的client.id（COUNT（DISTINCT（clients.id）））來獲得預期的結果，用於添加的客戶端數量，

$this->db->select('clients.id AS my_client,
    clients.name AS client_name,
    campaign.name AS campaign_name,
    DATE(clients.dateAdded) AS client_date,
    SUM(order.cost) AS order_cost,
    COUNT(DISTINCT(clients.id)) AS num_rows'); //changed the code here from COUNT(clients.id) AS num_rows

$this->db->from('clients');
$this->db->where('clients.adminId', $adminId);
$this->db->where('clients.is_deleted', 0);
$this->db->where('DATE(clients.dateAdded) >=', $from_date);
$this->db->where('DATE(clients.dateAdded) <=', $to_date);
$this->db->join('campaign', 'campaign.id = clients.campaignId', 'left');
$this->db->join('order', 'order.clientId = clients.id', 'left');
$this->db->group_by('campaign_name');
$query = $this->db->get();
return $query->result();

我不認為這是正確的方法。有沒有更好的方法來做到這一點。謝謝你的支持。