Question

我想从两个表中返回共享百分比计算摘要的结果，但我不知道如何执行此操作。我的表格如下：

表 pa

---+-----------+---------+-----------+---------+-----------+---------+----------+
id | product_1 | share_1 | product_2 | share_2 | product_3 | share_3 |  amount  |
---+-----------+---------+-----------+---------+-----------+---------+----------+
 1 |    3      |   50    |     2     |    50   |           |         |  5000    |
 2 |    2      |   50    |     1     |    25   |     4     |   25    |  10000   |
 3 |    5      |   50    |     4     |    50   |           |         |  7000    |
---+-----------+---------+-----------+---------+-----------+---------+----------+

表产品

---+-----------+
id | name      |
---+-----------+
 1 | Book      |
 2 | Pen       |
 3 | Ruler     |
 4 | Pencil    |
 5 | Calendar  |
---+-----------+

我希望结果如下：

Product_name | Total
-------------+----------
Book         | 2500
Pen          | 7500
Ruler        | 2500
Pencil       | 6000
Calendar     | 3500
-------------+----------
Grand Total  | 22000

到目前为止，我已尝试过此查询

$this->db->select('t1.name as product_name, sum(t2.amount) as total');
$this->db->from('products t1');
$this->db->join('pa t2', 't2.product_1 = t1.id OR t2.product_2 = t1.id OR t2.product_3 = t1.id', 'left');
$this->db->group_by('t1.name');
$query = $this->db->get();

SQL小提琴：http://sqlfiddle.com/#!2/471c4/1

但它没有返回我想要的结果，因为没有计算每种产品的份额百分比。

有没有办法只用SQL查询返回我想要的结果？或者我是否必须使用PHP递归计算？

Answer 1

您可以先通过取消隐藏数据来进行计算：

select p.name, sum(amount)
from ((select product_1 as pid, amount*share_1 / 100.0 as amount from pa) union all
      (select product_2 as pid, amount*share_2 / 100.0 as amount from pa) union all
      (select product_3 as pid, amount*share_3 / 100.0 as amount from pa)
     ) pp join
     product p
     on pp.pid = p.id
group by p.name

您可以在应用程序中或使用ROLLUP获取总数。

Answer 2

尝试以下SQL：

SELECT product_name, SUM(percentage)
FROM
(
    SELECT  t1.name as product_name, t2.share_1, t2.amount, (t2.share_1*t2.amount)/100 as percentage        
    FROM products t1 JOIN pa t2 ON  t2.product_1 = t1.id
    GROUP BY t1.name
    UNION
    SELECT  t1.name as product_name, t2.share_2, t2.amount, (t2.share_2*t2.amount)/100         as percentage        
    FROM products t1 JOIN pa t2 ON  t2.product_2 = t1.id
    GROUP BY t1.name
    UNION
    SELECT  t1.name as product_name, t2.share_3, t2.amount, (t2.share_3*t2.amount)/100 as percentage        
    FROM products t1 JOIN pa t2 ON  t2.product_3 = t1.id
    GROUP BY t1.name
) as temp_table
GROUP BY product_name

SqlFiddle Demo

两个表中的份额百分比计算摘要

2 个答案: