多個SQL查詢或光標？

Question

我需要幫助的東西似乎對我來說很複雜。

我做了一個查詢來創建一個tbl1，它是表Item和Warehouse的Cartesian乘積。它給的我帶回的所有項目中的所有倉庫：

SELECT i.ItemID, w.WarehouseID 
FROM Item i, Warehouse w 

我做了，我檢查了最後一個文檔以前或等於變量日期（@datevar），其數量規則之日起第二個查詢（TBL2） 1（PhysicalQtyRule = 1），這由項目和倉庫，從StockHistory表獲得現在

SELECT MAX(CreateDate) AS [DATE1], ItemID, Quantity, WarehouseID 
FROM StockHistory 
WHERE PhysicalQtyRule = 1 AND CreateDate <= @datevar 
GROUP BY ItemID, Quantity, WarehouseID 

，我需要更多的三個步驟：

1. 生成每個項目和倉庫含有第三表數量總和，但數量規則爲2（PhysicalQtyRule = 2）和tbl2.date（如果存在）與變量@datevar之間的日期，從表StockHistory獲取。類似的東西：

   SELECT ItemID, WarehouseID, SUM(Quantity) 
   FROM StockHistory 
   WHERE PhysicalQtyRule = 2 AND CreateDate > tbl2.DATE1 --If exists 
   AND CreateDate <= @datevar 
   GROUP BY ItemID, WarehouseID 
   

2. 生成每個項目和倉庫含有量的總和的第四表中，但數量的規則是3（PhysicalQtyRule = 3）和tbl2.date之間日期（如果有的話）和日期變量@datevar，從表StockHistory獲得。類似的東西：

   SELECT ItemID, WarehouseID, SUM(Quantity) 
   FROM StockHistory 
   WHERE PhysicalQtyRule = 3 AND CreateDate > tbl2.DATE1 --If exists 
   AND CreateDate <= @datevar 
   GROUP BY ItemID, WarehouseID 
   

3. 創建基於第一個的決賽桌，與和數量列，這樣的事情：

   SELECT i.ItemID, w.WarehouseID, tbl2.Quantity + tbl3.Quantity – tbl4.Quantity AS [Qty] 
   FROM Item i, Warehouse w 
   

我不知道是否需要遊標（對我而言是新事物）或多個查詢，但重要的是性能最好，因爲我的StockHistory表有數百萬條記錄。

任何人都可以幫助我嗎？謝謝！

一些樣本數據中，只有一個項目和一個倉庫：

+--------+-------------+------------+-----------------+----------+ 
| ItemID | WarehouseID | CreateDate | PhysicalQtyRule | Quantity | Balance | comments 
+--------+-------------+------------+-----------------+----------+ 
| 1234 |   11 | 2013-03-25 |    2 |  35 |  35 | Rule 2 = In 
| 1234 |   11 | 2013-03-28 |    3 |  30 |  5 | Rule 3 = Out 
| 1234 |   11 | 2013-04-01 |    1 |  3 |  3 | Rule 1 = Reset 
| 1234 |   11 | 2013-07-12 |    2 |  40 |  43 | Rule 2 = In 
| 1234 |   11 | 2013-09-05 |    3 |  20 |  23 | Rule 3 = Out 
| 1234 |   11 | 2013-12-31 |    1 |  25 |  25 | Rule 1 = Reset 
| 1234 |   11 | 2014-01-09 |    3 |  11 |  14 | Rule 3 = Out 
| 1234 |   11 | 2014-01-16 |    3 |  6 |  8 | Rule 3 = Out 

我想知道的任何變量日期的平衡。

Answer 1

沒有你的數據，我無法測試這個，但我相信這應該是你的解決方案。

SELECT i.ItemID 
    ,w.WarehouseID 
    ,[Qty] = tbl2.Quantity + tbl3.Quantity – tbl4.Quantity 
FROM Item i 
CROSS JOIN Warehouse w 
OUTER APPLY (
SELECT [DATE1] = MAX(sh.CreateDate) 
     ,sh.ItemID 
     ,sh.Quantity 
     ,sh.WarehouseID 
FROM StockHistory sh 
WHERE sh.PhysicalQtyRule = 1 AND sh.CreateDate <= @datevar 
AND i.ItemID = sh.ItemID 
    AND w.WarehouseID = sh.WarehouseID 
GROUP BY sh.ItemID, sh.Quantity, sh.WarehouseID) tbl2 
OUTER APPLY (
SELECT sh.ItemID 
    ,sh.WarehouseID 
    ,[Quantity] = SUM(sh.Quantity) 
FROM StockHistory sh 
WHERE sh.PhysicalQtyRule = 2 AND sh.CreateDate > tbl2.DATE1 --If exists 
AND sh.CreateDate <= @datevar AND i.ItemID = sh.ItemID 
AND w.WarehouseID = sh.WarehouseID 
GROUP BY sh.ItemID, sh.WarehouseID) tbl3 
OUTER APPLY (
SELECT sh.ItemID 
    ,sh.WarehouseID 
    ,[Quantity] = SUM(sh.Quantity) 
FROM StockHistory sh 
WHERE sh.PhysicalQtyRule = 3 AND sh.CreateDate > tbl2.DATE1 --If exists 
AND sh.CreateDate <= @datevar AND i.ItemID = sh.ItemID 
    AND w.WarehouseID = sh.WarehouseID 
GROUP BY sh.ItemID, sh.WarehouseID) tbl4