根据列值更新SQL表

I have a large set of data that needs to be updated based on price. Very simply, the price of an item in Code/Size 1 must be equal to or less than the Code/Size 2. Code/Size 2 must be equal to or less than Code/Size 3, and so on:

我有一大堆需要根据价格更新的数据。非常简单，代码/大小1中的项目的价格必须等于或小于代码/大小2.代码/大小2必须等于或小于代码/大小3，依此类推：

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

Must look like:

必须看起来像：

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

I've tried some self-joins and I'm basically losing my mind. Any help is sincerely appreciated.

我尝试了一些自我加入，我基本上都在失去理智。任何帮助都是真诚的感谢。

Thanks!

谢谢！

4 个解决方案

#1

For SQL-Server 2012, you can use this:

对于SQL-Server 2012，您可以使用：

; 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 ;

Tested at SQL-Fiddle

在SQL-Fiddle测试

#2

Does this get you what you need?

这能满足您的需求吗？

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)

#3

answer is Recursive CTE. not depends on the SQL SERVER version.

答案是递归CTE。不依赖于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

#4

Supposing t is your table's name:

假设t是你的表名：

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