如何 SQL 中另一个表中具有相同 id 的值的 select 总和

Question

我有两张桌子：

桌子套件

id_kit | id_product | quantity
1      | 5          | 5 
1      | 4          | 2 
1      | 10         | 10
2      | 12         | 1 
2      | 20         | 2

表产品

id_product | pco_cost 
5          | 100
4          | 50  
10         | 20 
12         | 10 
20         | 5 

我想要的结果

id_kit | cost_kit 
1 | 800

每个产品的成本总和乘以数量 其中 id_kit = "x"

编辑：（从评论中复制）：我试试这个：

SELECT 
  pco_cost * (SELECT pkt_quantity FROM cm_product_kit where kt_id_product_catalog = 20928) as pkt_cost 
FROM cm_product_cost 
where pco_prd_id_product = 20928

但只得到 1 个字段的结果，我希望所有具有相同 id 的项目返回每个产品的总和。

谢谢！

Answer 1

看起来像一个简单的聚合连接（过度乘法）。 第 1 - 15 行代表样本数据； 您需要的查询从第 16 行开始。

SQL> with
  2  kit (id_kit, id_product, quantity) as
  3    (select 1, 5,   5 from dual union all
  4     select 1, 4,   2 from dual union all
  5     select 1, 10, 10 from dual union all
  6     select 2, 12,  1 from dual union all
  7     select 2, 20,  2 from dual
  8    ),
  9  product (id_product, pco_cost) as
 10    (select  5, 100  from dual union all
 11     select  4,  50  from dual union all
 12     select 10,  20  from dual union all
 13     select 12,  10  from dual union all
 14     select 20,   5  from dual
 15    )
 16  select k.id_kit, sum(k.quantity * p.pco_cost) cost_kit
 17  from kit k join product p on k.id_product = p.id_product
 18  group by k.id_kit
 19  order by k.id_kit;

    ID_KIT   COST_KIT
---------- ----------
         1        800
         2         20

SQL>

Answer 2

DECLARE     @tableKit TABLE (id_kit int, id_product int, quantity int)
INSERT INTO @tableKit VALUES
            (1,  5 ,  5)
        ,   (1,  4 ,  2)
        ,   (1, 10 , 10)
        ,   (2, 12 ,  1)
        ,   (2, 20 ,  2)

DECLARE     @tableProduct   TABLE   (id_product int, pco_cost int)
INSERT INTO @tableProduct   VALUES
            ( 5 , 100)
        ,   ( 4 ,  50)
        ,   (10 ,  20)
        ,   (12 ,  10)
        ,   (20 ,   5)

SELECT  
        id_kit
    ,   cost_kit    =   SUM(cost_kit)
FROM    (   
            SELECT
                        id_kit      =   TK.id_kit
                    ,   cost_kit    =   TP.pco_cost * TK.quantity
            FROM        @tableKit       TK
                JOIN    @tableProduct   TP  ON  TP.id_product   =   TK.id_product
        )   R
GROUP BY id_kit