请求一个SQL的写法

[new4everlau]

有一个表，简化如下：包含所有出、入库记录，但是此表的所有出库（InOrOut标记为-1的记录）成本单价全部为空，求一个SQL，完成所有出库成本单价的更新语句。
出库成本单价采用移动加权平均算法。
移动加权平均单价= (本次收入前结存商品金额+本次收入商品金额)/(本次收入前结存商品数量+本次收入商品数量 )
原始记录如下：
InOrOut Date Qty UnitCost Cost
1 2017-09-01 100 23.00 2300.00
1 2017-09-10 400 22.50 9000.00
-1 2017-09-12 300 NULL NULL
1 2017-09-20 200 22.00 4400.00
-1 2017-09-25 300 NULL NULL
1 2017-09-30 333 20.00 6660.00
更新后结果为：
InOrOut Date Qty UnitCost Cost
1 2017-09-01 100 23.00 2300.00
1 2017-09-10 400 22.50 9000.00
-1 2017-09-12 300 A1 B1 --上面2条记录入库，其成本单价为（2300+9000）/（100+400） = 22.6，所以这条的出库成本单价A1 = 22.6，B1 = 300*22.6=6780
1 2017-09-20 200 22.00 4400.00
-1 2017-09-25 300 A2 B2 --此条出库成本单价为：上面结余成本/当前库存，即A2 = （2300+9000-6780+4400）/（100+400-300+200） = 8920/400 = 22.3，B2 = 6690
1 2017-09-30 333 20.00 6660.00

[RINK_1]

if OBJECT_ID(N'tempdb.dbo.#t') is not null
drop table #t
go

create table #t
(InOrOut int,
 io_date date,
 Qty int,
 UnitCost numeric(12,2),
 Cost numeric(12,2))
 
 insert into #t
 select 1,'2017-09-01',100,23,2300 union all
 select 1,'2017-09-10',400,22.5,9000 union all
 select -1,'2017-09-12',300,null,null union all
 select 1,'2017-09-20',200,22,4400 union all
 select -1,'2017-09-25',300,null,null union all
 select 1,'2017-09-30',333,20,6660 UNION ALL
  select -1,'2017-10-30',500,NULL,NULL
 

 with cte_1
 as
 ( select A.*,B.*,ROW_NUMBER() OVER (ORDER BY io_date) as seq 
   from #t A
   outer apply (select SUM(qty) as subtotal_qty,SUM(cost) as subtotal_cost from #t where io_date<A.io_date AND InOrOut=1) AS B
 where InOrOut=-1),
 
 cte_2
 as
 ( select A.*,
          subtotal_cost*1.0/subtotal_qty AS UNITCOST_NEW,
          A.Qty*(subtotal_cost*1.0/subtotal_qty) as cost_NEW,
          -1*A.Qty AS NEXT_QTY,
         -1*A.Qty*(subtotal_cost*1.0/subtotal_qty) AS NEXT_COST
   from cte_1 A
   where seq=1
   union all
   select A.*,
         (NEXT_COST+A.subtotal_cost)*1.0/(B.NEXT_QTY+A.subtotal_qty),
          (NEXT_COST+A.subtotal_cost)*1.0/(B.NEXT_QTY+A.subtotal_qty)*A.QTY,
          B.NEXT_QTY-A.Qty,
          B.NEXT_COST-((NEXT_COST+A.subtotal_cost)*1.0/(B.NEXT_QTY+A.subtotal_qty)*A.QTY)
   from cte_1 A
   join cte_2 B on A.seq=B.seq+1)
                
                
  SELECT * FROM cte_2
  

[qq_37921165]