sql - SQL中的库存平均成本计算

Question

我想使用平均值计算库存成本，但我有点卡在这里...

考虑一个简单的交易表 tr :(ids 是自动递增的，负交易量表示卖出交易)

order_id | volume | price | type
       1 |   1000 |   100 | B
       2 |   -500 |   110 | S
       3 |   1500 |    80 | B
       4 |   -100 |   150 | S
       5 |   -600 |   110 | S
       6 |    700 |   105 | B

现在我想知道每次交易后的总交易量和总成本。困难在于正确销售。在这一点上，卖出总是以平均成本计价(即卖出价格实际上与此处无关)，因此交易订单在这里确实很重要。

理想情况下，结果如下所示:

order_id | volume | price | total_vol | total_costs | unit_costs
       1 |   1000 |   100 |      1000 |      100000 |        100
       2 |   -500 |   110 |       500 |       50000 |        100
       3 |   1500 |    80 |      2000 |      170000 |         85
       4 |   -100 |   150 |      1900 |      161500 |         85
       5 |   -600 |   110 |      1300 |      110500 |         85
       6 |    700 |   105 |      2000 |      184000 |         92

现在，total_vol 很容易使用 sum(volume) over (...) ，另一方面总成本。我玩过窗口函数，但除非我遗漏了一些完全明显(或非常聪明)的东西，否则我认为它不能单独使用窗口函数来完成......

任何帮助，将不胜感激。 :)

更新:

这是我最终使用的代码，两个答案的组合(数据模型比我上面的简化示例稍微复杂一些，但您明白了):

select ser_num
  , tr_id
  , tr_date
  , action_typ
  , volume
  , price
  , total_vol
  , trunc(total_costs,0) total_costs
  , trunc(unit_costs,4) unit_costs
from itt
  model
    partition by (ser_num)
    dimension by (row_number() over (partition by ser_num order by tr_date, tr_id) rn)
    measures (tr_id, tr_date, volume, price, action_typ, 0 total_vol, 0 total_costs, 0 unit_costs)
    rules automatic order 
    ( total_vol[ANY] order by rn
      = nvl(total_vol[cv()-1],0) + 
        decode(action_typ[cv()], 'Buy', 1,  'Sell', -1) * volume[cv()]
    , total_costs[ANY] order by rn
      = case action_typ[cv()]
          when 'Buy' then volume[cv()] * price[cv()] + nvl(total_costs[cv()-1],0)
          when 'Sell' then total_vol[cv()] * nvl(unit_costs[cv()-1],price[cv()])
        end
    , unit_costs[ANY] order by rn
      = decode(total_vol[cv()], 0, unit_costs[cv()-1], 
        total_costs[cv()] / total_vol[cv()])
    )
order by ser_num, tr_date, tr_id 

一些观察:

当使用分区和对前一个单元格的引用 ( cv()-1 ) 时，维度必须以与整个模型子句相同的方式进行分区(这也是使用迭代编号可能很棘手的原因)

只要您在规则上指定正确的执行顺序，这里就不需要迭代(order by rn 编辑:Automatic order 自动执行此操作)

这里可能不需要自动订购，但它不会受到伤害。

Answer 1

您可以使用 MODEL 子句来执行此递归计算

创建示例表并插入数据

create table costs (order_id int, volume int, price numeric(16,4), type char(1));

insert into costs (order_id, volume, price) values (1,1000,100);
insert into costs (order_id, volume, price) values (2,-500,110);
insert into costs (order_id, volume, price) values (3,1500,80);
insert into costs (order_id, volume, price) values (4,-100,150);
insert into costs (order_id, volume, price) values (5,-600,110);
insert into costs (order_id, volume, price) values (6,700,105);

查询( EDITED 将 rules iterate(1000) 更改为 rules automatic order 实现了 MODEL 子句，因为它旨在发挥作用，即按顺序从上到下。它还使查询从 0.44 秒到 0.01 秒!)

select order_id, volume, price, total_vol, total_costs, unit_costs
    from (select order_id, volume, price,
                 volume total_vol,
                 0.0 total_costs,
                 0.0 unit_costs,
                 row_number() over (order by order_id) rn
          from costs order by order_id)
   model
         dimension by (order_id)
         measures (volume, price, total_vol, total_costs, unit_costs)
         rules automatic order -- iterate(1000)
         ( total_vol[any] = volume[cv()] + nvl(total_vol[cv()-1],0.0),
           total_costs[any] =
                    case SIGN(volume[cv()])
                    when -1 then total_vol[cv()] * nvl(unit_costs[cv()-1],0.0)
                    else volume[cv()] * price[cv()] + nvl(total_costs[cv()-1],0.0)
                    end,
           unit_costs[any] = total_costs[cv()] / total_vol[cv()]
         )
   order by order_id

输出

ORDER_ID VOLUME     PRICE      TOTAL_VOL   TOTAL_COSTS   UNIT_COSTS
1        1000       100        1000        100000        100
2        -500       110        500          50000        100
3        1500        80        2000        170000        85
4        -100       150        1900        161500        85
5        -600       110        1300        110500        85
6        700        105        2000        184000        92

这个站点有一个关于 MODEL 子句的很好的教程

http://www.sqlsnippets.com/en/topic-11663.html

上面数据的EXCEL表看起来像这样，公式向下延伸

    A         B       C      D          E                         F
 ---------------------------------------------------------------------------
1|  order_id  volume  price  total_vol  total_costs               unit_costs
2|                                   0                         0           0
3|  1           1000    100  =C4+E3     =IF(C4<0,G3*E4,F3+C4*D4)  =F4/E4
4|  2           -500    110  =C5+E4     =IF(C5<0,G4*E5,F4+C5*D5)  =F5/E5
5|  3           1500     80  =C6+E5     =IF(C6<0,G5*E6,F5+C6*D6)  =F6/E6
6|  4           -100    150  =C7+E6     =IF(C7<0,G6*E7,F6+C7*D7)  =F7/E7
7|  5           -600    110  =C8+E7     =IF(C8<0,G7*E8,F7+C8*D8)  =F8/E8
8|  6           700     105  =C9+E8     =IF(C9<0,G8*E9,F8+C9*D9)  =F9/E9