Solved

SQL update matching first record with closest time

Posted on 2009-05-15
2
512 Views
Last Modified: 2012-06-27
Hi
I have following sample data in different tables
HistorianData
     TIMESTAMP                  FieldX
1   15/10/08  00:00:00     NULL
2   15/10/08  00:01:00     NULL
3   15/10/08  00:02:00     NULL
...
X     15/10/09  23:59:00     NULL
X+1 16/10/09  00:00:00     NULL
X+2  16/10/09 00:01:00     NULL
XXX...      16/10/09  00:02:00

and so on...a date/time field with every minute and 0 seconds

I have another table DataDump with data like this

       TIMESTAMP                  FieldX
9     15/10/08  00:00:10       1
10   15/10/08  00:00:20       2
11   15/10/08  00:00:40       90
12   16/10/08  00:01:16       64
13   16/10/08  00:01:59       20
...
X     16/10/08  00:02:20       123


I want to set the FieldX of HistorianData to be FieldX of DataDump . Because in DataDump the TIMESTAMP isn't rounded down every minute so often there are not exact matches with HistorianData.
In the match I want to round the first record of every minute DOWN so that there is always a match, so in above I want

1 would be set to record ID 9
2 would be set to record ID 12
XXX would be set to record ID X

There are more than one record per minute in DataDump , I only want to match the closest record and ignore others.

Thanks in advance for help with transact-SQL.  If it helps, any records of TableX records can be deleted or modified, it will just be deleted anyway after update.

I have SQL server 2008

(I know TIMESTAMP isn't a good field name, please excuse it, but that's what data dump was....)
I used following SQL kindly made up on another question for EXACT matches...
 
update HistorianData set [ddd] = D.[ddd]
  from [DataDump] D
 where HistorianData.[TIMESTAMP] = D.[DataDump]

Open in new window

0
Comment
Question by:rwallacej
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
2 Comments
 
LVL 143

Accepted Solution

by:
Guy Hengel [angelIII / a3] earned 500 total points
ID: 24394210
something like this should do:
UPDATE t1
  SET fieldx = ( SELECT TOP 1 t2.Fieldx 
                 FROM table2 t2 
                 WHERE t2.TIMESTAMP >= DATEADD(minute, -1, t1.TIMESTAMP )
                   AND t2.TIMESTAMP <= DATEADD(minute, 1, t1.TIMESTAMP )
                )

Open in new window

0
 

Author Closing Comment

by:rwallacej
ID: 31581821
thank-you - this works
regards,
rwallacej
0

Featured Post

Visualize your virtual and backup environments

Create well-organized and polished visualizations of your virtual and backup environments when planning VMware vSphere, Microsoft Hyper-V or Veeam deployments. It helps you to gain better visibility and valuable business insights.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Hi all, It is important and often overlooked to understand “Database properties”. Often we see questions about "log files" or "where is the database" and one of the easiest ways to get general information about your database is to use “Database p…
This article explains how to reset the password of the sa account on a Microsoft SQL Server.  The steps in this article work in SQL 2005, 2008, 2008 R2, 2012, 2014 and 2016.
Nobody understands Phishing better than an anti-spam company. That’s why we are providing Phishing Awareness Training to our customers. According to a report by Verizon, only 3% of targeted users report malicious emails to management. With compan…
In a recent question (https://www.experts-exchange.com/questions/29004105/Run-AutoHotkey-script-directly-from-Notepad.html) here at Experts Exchange, a member asked how to run an AutoHotkey script (.AHK) directly from Notepad++ (aka NPP). This video…

762 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question