根據列值更新SQL表

Question

我有一大組數據需要根據價格進行更新。非常簡單，代碼/尺寸1中物品的價格必須等於或小於代碼/尺寸2.代碼/尺寸2必須等於或小於代碼/尺寸3，依此類推：

Item  Code Size Price 
------------------------------- 
66227019 OTH  1 $466 
66227019 OTH  2 $486 
66227019 OTH  3 $476 
66227019 OTH  4 $537 

66227019 IVC  1 $458 
66227019 IVC  2 $428 
66227019 IVC  3 $458 
66227019 IVC  4 $458 

必須像：

Item  Code Size Price 
------------------------------- 
66227019 OTH  1 $466 
66227019 OTH  2 $486 
66227019 OTH  3 $486 
66227019 OTH  4 $537 

66227019 IVC  1 $458 
66227019 IVC  2 $458 
66227019 IVC  3 $458 
66227019 IVC  4 $458 

我已經嘗試了一些自聯接和我基本上失去了我的腦海裏。任何幫助真誠讚賞。

謝謝！

Answer 1

對於SQL-Server 2012中，您可以使用此：

; WITH cte AS 
(SELECT *, 
     MaxPrice = MAX(Price) 
        OVER (PARTITION BY Item, Code 
          ORDER BY Size 
          ROWS BETWEEN UNBOUNDED PRECEDING 
            AND 1 PRECEDING 
         ) 
    FROM Products 
) 
UPDATE cte 
SET Price = MaxPrice 
WHERE Price < MaxPrice ; 

測試在SQL-Fiddle

Answer 2

這是否得到你所需要的？

UPDATE LaterRec 
SET Price = PrevRec.Price 
FROM Data AS LaterRec 
    INNER JOIN Data AS PrevRec ON LaterRec.Item = PrevRec.Item AND LaterRec.Code = PrevRec.Code AND PrevRec.Size < LaterRec.Size 
WHERE 
     PrevRec.Price > LaterRec.Price 
    -- Disregard this entry if there's a record *between* PrevRec and LaterRec 
    AND NOT EXISTS (SELECT * FROM Data AS Intrmdt WHERE LaterRec.Item = Intrmdt.Item AND LaterRec.Code = Intrmdt.Code AND Intrmdt.Size > PrevRec.Size AND Intrmdt.Size < LaterRec.Size) 

Answer 3

答案是遞歸的CTE。不依賴於SQL SERVER版本。

DECLARE @t TABLE 
    (
     item  INT 
     ,code  sysname 
     ,SIZE  INT 
     ,price  INT 
    ) 
    INSERT INTO @t(item, code, SIZE, price) 
       SELECT 1,'oth',1,466 
    UNION ALL SELECT 1,'oth',2,486 
    UNION ALL SELECT 1,'oth',3,476 
    UNION ALL SELECT 1,'oth',4,537 

    UNION ALL SELECT 1,'ivc',1,458 
    UNION ALL SELECT 1,'ivc',2,428 
    UNION ALL SELECT 1,'ivc',3,458 
    UNION ALL SELECT 1,'ivc',4,458 

    SELECT * FROM @t 

    ;WITH cte1 (item,code,size,price,rownum1,rownum2) 
    AS 
    (
     SELECT *, ROW_NUMBER() OVER (PARTITION BY item,code ORDER BY item,code,SIZE) AS rownum1, ROW_NUMBER() OVER (ORDER BY item,code,SIZE) AS rownum2 
     FROM @t 
    ), 
    cte2 (item,code,size,price,rownum1,rownum2) 
    AS 
    (
     SELECT * 
     FROM cte1 t1 
     WHERE rownum2=1 

     UNION ALL 

     SELECT t1.item,t1.code,t1.size 
       ,CASE WHEN t1.price>=t2.price THEN t1.price 
         WHEN t1.price<t2.price THEN t2.price 
       END AS proce 
       ,t1.rownum1,t1.rownum2 
     FROM cte2 t2 
     JOIN cte1 t1 
      ON t2.rownum2+1=t1.rownum2 
    ) 
    SELECT item,code,size,price FROM cte2 

Answer 4

假設t是你的表的名稱：

update t set price=p 
from (
    select nxt.item i,nxt.code c,nxt.size s,max(cur.price) p 
    from t cur join t nxt 
    on (cur.item=nxt.item and cur.code=nxt.code 
    and cur.size<nxt.size and cur.price>nxt.price) 
    group by nxt.item,nxt.code,nxt.size  
) a 
where item=i and code=c and size=s