Question

在这里，我想将上一行余额值输入到我的字段中。

customer_id＆＃39; 16＆＃39;的最后一个ID余额是200，但我希望将前一个ID值输入到该字段中，这是我的表

    id  order_id    customer_id  amount     actual_amount   paid_amount     balance     type
    25  11            16                        100.00        50.00         50.00       Cash
    26  12            16                        200.00        100.00        100.00      Cash
    27  13            16                        150.00        100.00        50.00       Cash
    28  14            16                        300.00        250.00        50.00       Cash
    29  14            16                        170.00        100.00        70.00       Cash
    30  15            16         100            170.00        70.00         100.00      Cash
    31  16            16         400            500.00        300.00        200.00      Cash

这是我的模特

public function order_balance($order_code)
{
    $this->db->join('services','payment.customer_id=services.customer_id','left');
    $this->db->select('payment.*,payment.balance,payment.actual_amount,payment.customer_id');
    $this->db->order_by('payment.id','desc');
    $query = $this->db->get_where('payment',array('code' => $order_code));
    return $query->previous_row();
}

这是我的控制：

 public function final_payment($order_code)
{
    $data['active_mn']='';
    $data['result'] = $this->Account_model->order_balance($order_code); 
    $this->load->view('final_payment',$data);
}

我的服务表如下所示：

    id  code      customer_id   particulars     
    11  ORD00011    16              phone   
    12  ORD00012    16              gdf     
    13  ORD00013    16              ghgfh   
    14  ORD00014    16               tv     
    15  ORD00015    16              ghfg    
    16  ORD00016    16               tv     
    17  ORD00017    16              gdfg    
    18  ORD00018    16              desk    
    19  ORD00019    16              gdf

我的结果应该是这样的：

 id      order_id    customer_id     amount    actual_amount   paid_amount  balance     type
 31        16            16           400         500.00         300.00     100.00      Cash

Answer 1

此处的一个选项是与payment表进行自我加入，加入customer_id和order_id列。您可以添加另一个连接函数调用，然后在您的选择中使用结果。以下解决方案使用原始查询，因为Codeigniter似乎不能容忍连接条件中的算术：

public function order_balance($order_code)
{
    $this->db->query("SELECT p1.*, p2.balance AS previous_balance FROM payment p1 INNER JOIN payment p2 ON p1.order_id = p2.order_id + 1 AND p1.customer_id = p2.customer_id LEFT JOIN services s ON p1.customer_id = s.customer_id ORDER BY p1.id DESC");
    $query = $this->db->get_where('p1', array('code' => $order_code));
    return $query->previous_row();
}

查询的格式为：

SELECT p1.*, p2.balance AS previous_balance
FROM payment p1 INNER JOIN payment p2
    ON p1.order_id = p2.order_id + 1 AND
       p1.customer_id = p2.customer_id
LEFT JOIN services s
    ON p1.customer_id = s.customer_id
ORDER BY p1.id DESC

Answer 2

有很多方法可以写这个。这是一种方式。我不知道codeigniter，所以你必须对它进行逆向工程......

SELECT a.id
     , a.order_id
     , a.customer_id
     , a.amount
     , a.actual_amount
     , a.paid_amount
     , b.balance 
     , a.type
  FROM 
     ( SELECT x.*
            , MAX(y.id) prev 
         FROM payment x 
         JOIN payment y 
           ON y.id < x.id 
          AND y.customer_id = x.customer_id 
        GROUP 
           BY x.id
     ) a 
  JOIN payment b 
    ON b.id = a.prev 
 ORDER 
    BY id DESC LIMIT 1;

要获取的上一行值

2 个答案: