选择价格不变的行 [英] Select rows where price didn't change

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本文介绍了选择价格不变的行的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!

问题描述

假设您有一个类似的表(使用SQL Server 2008,没有审核日志-表很大):

Suppose you have a table like (am using SQL Server 2008, no audit log - table is HUGE):

 SecID | Date    | Price
 1       1/1/11      10
 1       1/2/11      10
 1       1/3/11      5
 1       1/4/11      10
 1       1/5/11      10

假设此表非常庞大(数百万行用于不同的secID和日期)-价格更改后,我想返回记录(寻找比使用游标和迭代更好的东西):

Suppose this table is HUGE (millions of rows for different secIDs and Date) - I would like to return the records when the price changed (looking for something better than using a cursor and iterating):

我正试图弄清楚如何获得:

Am trying to figure out how to get:

 SecID | StartDate | EndDate | Price
 1        1/1/11      1/2/11    10
 1        1/3/11      1/3/11    5
 1        1/4/11      1/5/11    10

即另一种查看方式是,我正在寻找价格保持不变的日期范围.

i.e. another way to look at it is that I am looking for a range of dates where the price has stayed the same.

推荐答案

这是一个孤岛"问题.

declare @Yourtable table
 (SecID int, Date Date, Price int)

 INSERT INTO @Yourtable
SELECT 1,GETDATE()-5,10 union all
SELECT 1,GETDATE()-4,10 union all
SELECT 1,GETDATE()-3,5 union all
SELECT 1,GETDATE()-2,10 union all
SELECT 1,GETDATE()-1, 10

;WITH cte AS
(
SELECT SecID,Date,Price,
       ROW_NUMBER() OVER (PARTITION BY SecID ORDER BY Date) -
       ROW_NUMBER() OVER (PARTITION BY Price, SecID ORDER BY Date) AS Grp
FROM @Yourtable
)
SELECT SecID,Price, MIN(Date) StartDate, MAX(Date) EndDate
FROM cte
GROUP BY SecID, Grp, Price
ORDER BY SecID,  MIN(Date)

这篇关于选择价格不变的行的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!

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