如何 SQL 中另一個表中具有相同 id 的值的 select 總和

Question

我有兩張桌子：

桌子套件

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

表產品

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

我想要的結果

id_kit | cost_kit 
1 | 800

每個產品的成本總和乘以數量 其中 id_kit = "x"

編輯：（從評論中復制）：我試試這個：

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 個字段的結果，我希望所有具有相同 id 的項目返回每個產品的總和。

謝謝！

Answer 1

看起來像一個簡單的聚合連接（過度乘法）。 第 1 - 15 行代表樣本數據； 您需要的查詢從第 16 行開始。

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