查询交易中的更新库存数量[关闭]

Question

我的查询有问题，因为我必须从不同的 stock_code 中扣除产品的数量。

假设客户将以 item_code (I0015) 购买 20 个数量的产品。首先我要在stock_code（ST0016）中减去12个数量，库存变为0，剩下的8个数量在stock_code（ST0012）中扣除，数量的扣除是根据stock_expired的升序。

如何在 MySQL 中查询？太感谢了！高度赞赏答案。我的表名是stocks_table

Answer 1

代码是否低于解决方案 (fiddle)？

with cte as(
select * from(
    select *, case when cumulsum <= TotalRequiredQuantity then 0 else cumulsum-TotalRequiredQuantity end NewQuantity 
     from(
       select *, 20 TotalRequiredQuantity,/*Set valid quantitity*/
          sum(stock_quantity) over(partition by item_code order by stock_expired) cumulsum
       from stocks_table
       where item_code = 'I0015'/*Set valid item_code*/
    )q
)q1
where stock_quantity>=NewQuantity)

update stocks_table st
join cte on st.id=cte.id
set st.stock_quantity = NewQuantity

没有公用表表达式：

update stocks_table st
join(
  select * from(
    select *
    ,case when cumulsum <= TotalRequiredQuantity then 0 else cumulsum-TotalRequiredQuantity end NewQuantity 
     from(
       select *, 20 TotalRequiredQuantity,/*Set valid quantitity*/
          sum(stock_quantity) over(partition by item_code order by stock_expired) cumulsum
       from stocks_table
       where item_code = 'I0015'/*Set valid item_code*/
    )q
  )q1
  where stock_quantity>=NewQuantity
)cte on st.id=cte.id
set st.stock_quantity = NewQuantity