采购订单号以履行客户订单号 - SQL

Question

order	Qty	Inventory	Type
1001	-1	-1	Customer Order
1002	-1	-2	Customer Order
1003	-1	-3	Customer Order
1004	-1	-4	Customer Order
1005	-5	-9	Customer Order
1006	3	-6	Purchase Order
1007	6	0	Purchase Order

通过上表，我们能否找到满足客户订单的采购订单号。
示例：

order #	Qty	Inventory	Type	Purchase order # that will fulfil order
1001	-1	-1	Customer Order	1006
1002	-1	-2	Customer Order	1006
1003	-1	-3	Customer Order	1006
1004	-1	-4	Customer Order	1007
1005	-5	-9	Customer Order	1007
1006	3	-6	Purchase Order
1007	6	0	Purchase Order

SQL

SELECT *
        , CASE WHEN Inventory >= 0 THEN OrderNumber
               ELSE LEAD(CASE WHEN QTY > 0 THEN OrderNumber END) IGNORE NULLS
                    OVER(ORDER BY OrderNumber)
          END PurchaseOrderNoToFulfil
FROM OrderTable;

上述查询不跟踪已使用的采购订单。例如，它显示了客户订单 # 1004 和 1005 的采购订单 # 1006。由于 1006 只有 3 个可用数量，因此它可以满足订单 1003，但不能超过此数量。

更多上下文：
在订单 1001 上，库存为 -1（超卖）。订单 1002，库存为 -2，依此类推。在订单 1006 上，有一个数量为 3 的传入采购订单来履行之前的客户订单。但是3的数量最多只能完成1003个订单。1004和1005订单要等到1007 PO进来。

Answer 1

您可以使用递归 CTE：

with recursive orders as (
   select row_number() over (order by `order`) o, * from ords
),
cte(id, r_id, s) as (
    select min(o.o), o1.o, o.qty + o1.qty from orders o 
    join orders o1 on o1.qty + o.qty >= 0 where o.qty < 0 and o1.qty = (select min(o2.qty) from orders o2 where o2.qty > 0)
    union all
    select c.id + 1, case when c.s + o1.qty >= 0 or o3.o is null then c.r_id else o3.o end, 
        case when c.s + o1.qty >= 0 then c.s + o1.qty else c.s + o1.qty + o3.qty end 
    from cte c join orders o1 on c.id + 1 = o1.o 
    left join orders o3 on o3.o > c.r_id where c.id + 1 <= (select max(o2.o) from orders o2 where o2.qty < 0)
)
select o.*, c.r_id from orders o left join cte c on o.o = c.id

Answer 2

我认为这给了我符合您要求的结果。也许你会发现它很有用。

with C as (
    select ordernum, -inventory as inventory,
        sum(-qty) over (order by ordernum) as fulfilled
    from O where "Type" = 'Customer Order'
), P as (
    select *, sum(qty) over (order by ordernum) as POed
    from O where "Type" = 'Purchase Order')
select ordernum, inventory, PO, POed
from C outer apply (
    select min(ordernum) as PO, min(POed) as POed from P where POed >= fulfilled
) oa

https://dbfiddle.uk/?rdbms=sqlserver_2014&fiddle=25a4efd31efc0827940a83b8658eb2b2

用标量子查询重写：

with C as (
    select ordernum, -inventory as inventory,
        sum(-qty) over (order by ordernum) as fulfilled
    from O where "Type" = 'Customer Order'
), P as (
    select *, sum(qty) over (order by ordernum) as POed
    from O where "Type" = 'Purchase Order')
select ordernum, inventory,
    (select min(ordernum) as PO from P where POed >= fulfilled) as PO
from C