Question

这是一个有效的mysql语句

update inventory i 
inner join (
    select ingredient_id, sum(amount) amount
    from product_ingredient p
    group by ingredient_id
) p on i.ingredient_id = p.ingredient_id 
set i.amount = i.amount - p.amount

这些是我数据库中的表

ORDER_ITEMS

+----------+--------+-----------------+------------+
| order_id |item_id |    item_name    |  quantity  |
+----------+--------+-----------------+------------+
|     1    |   1    |      coffee     |     2      |
|     1    |   2    |      shake      |     2      |
|     2    |   3    |    icecream     |     3      |
+----------+--------+-----------------+------------+

PRODUCT_INGREDIENT：

+--------+-----------------+--------+
|item_id | ingredient_id   | amount |
+--------+-----------------+--------+
|   1    |      123        |  10    |
|   1    |      124        |  15    |
|   1    |      125        |  10    |
|   2    |      124        |  15    |
|   2    |      123        |  10    |
|   2    |      126        |  15    |
|   3    |      124        |  15    |
|   3    |      123        |  10    |
|   3    |      126        |  15    |
+--------+-----------------+--------+

库存：

+--------+-----------------+--------+
|  id    | ingredient_id   | amount |
+--------+-----------------+--------+
|   1    |      123        |  100   |
|   2    |      124        |  100   |
|   3    |      125        |  100   |
|   4    |      126        |  100   |
+--------+-----------------+--------+

我需要为sql放置一个where语句，以便仅扣除order_id = 1 而不是全部都放在order_items表中

Answer 1

您可以将ORDER_ITEMS item_id与子查询p Ingredient_id结合起来

update inventory i 
inner join (
    select ingredient_id, sum(amount) amount
    from product_ingredient p
    group by ingredient_id
) p on i.ingredient_id = p.ingredient_id 
INNER JOIN PRODUCT_INGREDIENT p1 on p1.ingredient_id = p.ingredient_id
INNER JOIN ORDER_ITEMS o ON o.item_id = p1.item_id
set i.amount = i.amount - p.amount
WHER o.order_id  = 1

根据您的评论，您可能还需要item_id子查询

  update inventory i 
  inner join ( 
    select item_id, ingredient_id, sum(amount) amount 
    from product_ingredient p 
    group by item_id, ingredient_id 
    ) p on i.ingredient_id = p.ingredient_id 
    INNER JOIN ORDER_ITEMS o ON o.item_id = p.item_id 
    set i.amount = i.amount - p.amount 
    WHERE o.order_id = 1

基于您在注释中提供的结果，可能是您需要在product_ingredient和ORDER_ITEMS之间为join_id = 1联接的子查询

UPDATE inventory i 
INNER  JOIN (
  select p.ingredient_id, sum(p.amount) amount
  from product_ingredient p 
  INNER JOIN  order_items o on o.item_id = p.item_id
  WHERE o.order_id = 1
  GROUP BY p.ingredient_id
) p ON  i.ingredient_id = p.ingredient_id 
SET i.amount = i.amount - p.amount

我有一个有效的查询，但我需要在其中添加一个where子句

1 个答案: