库存数量如何写SQL需要根据之前的订单计算

Question

我有两个 table，一个用于当前产品总库存，一个用于产品订单。

STOCK_TB

PRODUCT_ID STOCK_QTY 
   A          20
   B          15
   C          10


ORDER_TB

ORDER_DATE PRODUCT_ID ORDER QTY
2015-03-01    A         5
2015-03-02    A         3
2015-03-02    B         4
2015-03-03    C         1
2015-03-04    C         3

我想要 select 月度库存数量报告的数据，如下所示。假设报表是在 3 月 5 日生成的

Stock Quantity of March:

                       Daily Stock Qty
Product ID  1   2   3   4   5  6  7 ... 28 29 30 31
    A      23  20  20  20  20  0  0      0  0  0  0
    B      19  15  15  15  15  0  0      0  0  0  0          
    C      14  14  13  10  10  0  0      0  0  0  0

往期库存数量以收盘日为准（即：以上3月2日指3月2日23:59:99.999）

超出当前日期的任何日期的数量都将为 0

我们没有 table 来保留每日库存，只有当前库存。所以这意味着要获取以前日期的库存，我必须向后添加产品订单量。

如何编写此类查询？对于日期列，我可以将它们固定在 1 到 31 之间，因为我可以根据应用程序中的月份隐藏未使用的日期。但我不太确定如何在 SQL 中编写逻辑，以便在以前的日期向当前库存添加订单数量。

Answer 1

6天查询示例（其他25天相同:-)

DECLARE @FirstOfMonth AS DATETIME = DATEADD(month, DATEDIFF(month, 0, GETDATE()), 0) 

SELECT 
    CASE WHEN DAY(GETDATE()) < 1 THEN 0 ELSE S.STOCK_QTY + ISNULL((SELECT SUM(O.ORDER_QTY) FROM ORDER_TB O WHERE O.PRODUCT_ID = S.PRODUCT_ID AND O.ORDER_DATE > DATEADD(day, 0, @FirstOfMonth)), 0) END _1,
    CASE WHEN DAY(GETDATE()) < 2 THEN 0 ELSE S.STOCK_QTY + ISNULL((SELECT SUM(O.ORDER_QTY) FROM ORDER_TB O WHERE O.PRODUCT_ID = S.PRODUCT_ID AND O.ORDER_DATE > DATEADD(day, 1, @FirstOfMonth)), 0) END _2,
    CASE WHEN DAY(GETDATE()) < 3 THEN 0 ELSE S.STOCK_QTY + ISNULL((SELECT SUM(O.ORDER_QTY) FROM ORDER_TB O WHERE O.PRODUCT_ID = S.PRODUCT_ID AND O.ORDER_DATE > DATEADD(day, 2, @FirstOfMonth)), 0) END _3,
    CASE WHEN DAY(GETDATE()) < 4 THEN 0 ELSE S.STOCK_QTY + ISNULL((SELECT SUM(O.ORDER_QTY) FROM ORDER_TB O WHERE O.PRODUCT_ID = S.PRODUCT_ID AND O.ORDER_DATE > DATEADD(day, 3, @FirstOfMonth)), 0) END _4,
    CASE WHEN DAY(GETDATE()) < 5 THEN 0 ELSE S.STOCK_QTY + ISNULL((SELECT SUM(O.ORDER_QTY) FROM ORDER_TB O WHERE O.PRODUCT_ID = S.PRODUCT_ID AND O.ORDER_DATE > DATEADD(day, 4, @FirstOfMonth)), 0) END _5,
    CASE WHEN DAY(GETDATE()) < 6 THEN 0 ELSE S.STOCK_QTY + ISNULL((SELECT SUM(O.ORDER_QTY) FROM ORDER_TB O WHERE O.PRODUCT_ID = S.PRODUCT_ID AND O.ORDER_DATE > DATEADD(day, 5, @FirstOfMonth)), 0) END _6

    FROM STOCK_TB S

请注意，我使用的是 > DATEADD 而不是 >= DATEADD，但我不太确定...您在本月第一天下的订单是什么时候计算的？

第二种解决方案，但我认为复杂性不会有太大变化：

DECLARE @FirstOfMonth AS DATETIME = DATEADD(month, DATEDIFF(month, 0, GETDATE()), 0) 
DECLARE @Today AS DATETIME = DATEADD(dd, DATEDIFF(dd, 0, GETDATE()), 0)

;WITH Days(d, dat) AS
(
    SELECT 1, @FirstOfMonth
    UNION ALL
    SELECT d+1, DATEADD(day, 1, dat) FROM Days WHERE d < DATEPART(day, @today)
)

, Work1 AS (
    SELECT PRODUCT_ID, STOCK_QTY + ISNULL((SELECT SUM(O.ORDER_QTY) FROM ORDER_TB O WHERE O.PRODUCT_ID = S.PRODUCT_ID AND O.ORDER_DATE > dat), 0) STOCK_TB, d FROM STOCK_TB S, Days 
)

SELECT PRODUCT_ID,
    ISNULL(MAX(CASE WHEN d = 1 THEN STOCK_TB END), 0) _1,
    ISNULL(MAX(CASE WHEN d = 2 THEN STOCK_TB END), 0) _2,
    ISNULL(MAX(CASE WHEN d = 3 THEN STOCK_TB END), 0) _3,
    ISNULL(MAX(CASE WHEN d = 4 THEN STOCK_TB END), 0) _4,
    ISNULL(MAX(CASE WHEN d = 5 THEN STOCK_TB END), 0) _5,
    ISNULL(MAX(CASE WHEN d = 6 THEN STOCK_TB END), 0) _6,
    ISNULL(MAX(CASE WHEN d = 7 THEN STOCK_TB END), 0) _7,
    ISNULL(MAX(CASE WHEN d = 8 THEN STOCK_TB END), 0) _8
    FROM Work1 GROUP BY PRODUCT_ID

在这里，我使用花哨的递归查询来构建一个 table 天 1...(today)，然后我构建一个 Work1 中间体，其中包含每天的所有库存数量（所以 x products * y days 行），然后我将它们分组

第三种可能性：双重递归查询（一种计算数字 1...31，另一种计算运行总数），加上最后的 GROUP BY 与前面的示例几乎相同。

DECLARE @FirstOfMonth AS DATETIME = DATEADD(month, DATEDIFF(month, 0, GETDATE()), 0) 
DECLARE @Today AS DATETIME = DATEADD(dd, DATEDIFF(dd, 0, GETDATE()), 0)

;WITH Days(d, dat) AS
(
    SELECT DATEPART(day, @Today), @Today dat
    UNION ALL
    SELECT d-1, DATEADD(day, -1, dat) dat 
        FROM Days 
        WHERE d > 1
)

# Product Days x STOCK_TB with a LEFT JOIN on ORDER_TB.
, Work1 AS (
    SELECT S.PRODUCT_ID, d, dat, S.STOCK_QTY, ISNULL(O.ORDER_QTY, 0) ORDER_QTY
        FROM Days
        CROSS JOIN STOCK_TB S # Full cartesian product, JOIN without conditions
        LEFT JOIN ORDER_TB O ON dat = O.ORDER_DATE AND S.PRODUCT_ID = O.PRODUCT_ID
)

# Second recursive query to do the running total
, Days2(PRODUCT_ID, d, dat, STOCK_QTY) AS 
(
    SELECT PRODUCT_ID, d, dat, STOCK_QTY 
        FROM Work1 
        WHERE d = DATEPART(day, @Today)
    UNION ALL
    SELECT d.PRODUCT_ID, d.d - 1, w.dat, d.STOCK_QTY + w.ORDER_QTY 
        FROM Days2 d 
        INNER JOIN Work1 w ON d.PRODUCT_ID = w.PRODUCT_ID AND d.d /* - 1 */ = w.d 
        WHERE d.d > 1
)

SELECT PRODUCT_ID,
    ISNULL(MAX(CASE WHEN d = 1 THEN STOCK_QTY END), 0) _1,
    ISNULL(MAX(CASE WHEN d = 2 THEN STOCK_QTY END), 0) _2,
    ISNULL(MAX(CASE WHEN d = 3 THEN STOCK_QTY END), 0) _3,
    ISNULL(MAX(CASE WHEN d = 4 THEN STOCK_QTY END), 0) _4,
    ISNULL(MAX(CASE WHEN d = 5 THEN STOCK_QTY END), 0) _5,
    ISNULL(MAX(CASE WHEN d = 6 THEN STOCK_QTY END), 0) _6,
    ISNULL(MAX(CASE WHEN d = 7 THEN STOCK_QTY END), 0) _7,
    ISNULL(MAX(CASE WHEN d = 8 THEN STOCK_QTY END), 0) _8
    FROM Days2 GROUP BY PRODUCT_ID

注意 /* - 1 */ 注释部分。取消注释，您可以控制每月第一天的值的使用方式。

库存数量如何写SQL需要根据之前的订单计算

How to write SQL for stock quantity that requires calculation from previous orders

sql

sql-server-2008-r2