SQL：在同一個表中插入新創建的列

Question

我有如下表：

create table Finance 
(
     [Product] int 
     ,[Timestamp] datetime 
     ,[Price] numeric(16, 4) 
) 

INSERT INTO Finance([Product], [Timestamp], [Price]) 
     VALUES 
       (5678, '20080101 12:00:00', 12.34) 
      ,(5678, '20080101 12:01:00', NULL) 
      ,(5678, '20080101 12:02:00', NULL) 
      ,(5678, '20080101 12:03:00', 23.45) 
      ,(5678, '20080101 12:04:00', NULL) 
      ,(5679, '20080101 13:04:00', NULL) 
      ,(5679, '20080101 13:05:00', 30.35) 
      ,(5679, '20080101 13:06:00', NULL) 

和下面的查詢將返回所需的輸出：

SELECT ISNULL(A.Price, B.Price) N_Price -- A.Product, A.Timestamp, A.Price, 
FROM Finance A 
OUTER APPLY ( SELECT TOP 1 * 
      FROM Finance 
      WHERE Product = A.Product AND Timestamp < A.Timestamp 
      AND Price IS NOT NULL 
      ORDER BY Product, Timestamp DESC) B 

而且我想插入列N_Price返回通過查詢到原始財務表。有沒有簡單快捷的方法，該怎麼做？

Answer 1

這應該一次更新工作將列

alter table finance add n_price numeric(16,1) 


update a 
set n_price=ISNULL(A.Price, B.Price) 
from finance a 
outer apply 
(
SELECT TOP 1 price 
      FROM Finance 
      WHERE Product = A.Product AND Timestamp < A.Timestamp 
      AND Price IS NOT NULL 
      ORDER BY Product, Timestamp DESC) B