在codeigniter中使用一对多关系连接三个表

Question

我在codeigniter做一个项目。我想加入三个表

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

广告系列（ID，名称，adminId）和

订单（id，name，cost，dateAdded，clientId）。

从这些表中我想选择（在两个日期之间）添加的客户数量，活动名称和客户的总订单成本。当我加入两个表（客户和活动）时，它返回正确的结果。

我使用的查询是

$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();

但当我加入三个表（客户，活动，订单）时，它没有返回正确的结果。客户和订单之间的关系是一对多的。如果一个客户可以有多个订单。所以它不会给出正确的总值在两个日期之间添加的客户端数。我用来连接三个表的连接查询是

$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这样做。谢谢你提前

Answer 1

我通过计算不同的client.id（COUNT（DISTINCT（clients.id）））来获得预期的结果，用于添加的客户端数量，

$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();

我不认为这是正确的方法。有没有更好的方法来做到这一点。谢谢你的支持。