Solved

Sql query to compare where rows have the same value in different columns

Posted on 2014-04-02
9
7,699 Views
Last Modified: 2014-04-02
Have a sample table as follows:

  ID     Old    New
123       a         b
123       b         a
456       a         b
456       b         c

Would like to write a query to select where an ID has the same Old value as it does a New value.

Basically, looking for where the old value was changed and then changed back to the current value, and what those 2 values would be.

So the result set I want back is:

  ID     Old    New    Newest
123      a          b          a

I would not want to get any of the 456 IDs back because that went from a to b to c, not back to a again.

Hope this is enough information.

Thanks!
0
Comment
Question by:flip4h
[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
  • 3
  • 3
  • 3
9 Comments
 
LVL 74

Expert Comment

by:sdstuber
ID: 39972642
how do we know the order of the rows?


123       a         b
123       b         a

could just as easily be

123       b         a
123       a         b


we have no way of knowing by looking at your data whether it changed from A to B to A
or from B to A to B
0
 
LVL 74

Accepted Solution

by:
sdstuber earned 500 total points
ID: 39972647
If we can make the assumption that order should be alphabetical based on the "old" column then try this...


SELECT o.old, o.new, n.new
  FROM yourtable o, yourtable n
 WHERE o.id = n.id AND o.new = n.old AND n.old > o.old

If there is some other criteria for determining which row came first, then please elaborate
0
 
LVL 32

Expert Comment

by:awking00
ID: 39972662
Is there any sort of change date available or perhaps some other indicator as to the order of change?
0
Salesforce Made Easy to Use

On-screen guidance at the moment of need enables you & your employees to focus on the core, you can now boost your adoption rates swiftly and simply with one easy tool.

 

Author Comment

by:flip4h
ID: 39972693
Thanks for looking into this.

Yes, there would be a change date associated, I created a dummy "table" for this example.  Just think the order it is in is the indicator of change, added a Change# as the indicator:

So table could be this:

  ID     Change#    Old    New
123         1             a         b
123         2             b         a
456         1             a         b
456         2             b         c
0
 
LVL 32

Expert Comment

by:awking00
ID: 39972713
Is it possible for it to be something like this?
123         1             a         b
123         2             b         a
456         1             a         b
456         2             b         c
456         2             c         b  (or a)
0
 
LVL 32

Expert Comment

by:awking00
ID: 39972719
The last line should have had a Change# of 3
0
 

Author Comment

by:flip4h
ID: 39972749
Yes that scenario would be possible.

A little more background on scenario

This table is an audit table, when a change is made, a new record is created.  So could have numerous change#.  Trying to find out if an ID is being changed and then changed back.  So it would not matter what change# it is, just whether or not for the same ID if that record had an old value that matched the new value (but going at least in the order of the change#).

So in the scenario you just gave, no matter if that chnage# 3 has a or b as its new value, it would need to show.

Because
Change# 1 has a as old value
Change# 2 has b as old value
So if Change# 3 has a as new value, then because 3 > 1 and change# 1 old = change# 3 new, then it would show
If Change# 3 has b as new value, then because 3 > 2 and change# 2 old = change# 3 new, then it would show
Hope this explains it more!

Thanks again.
0
 

Author Comment

by:flip4h
ID: 39972803
Which I believe using sdstuber's query, and modifying it to look like:

SELECT o.old, o.new, n.new
  FROM yourtable o, yourtable n
 WHERE o.task_id = n.task_id AND o.old_value = n.new_value and o.change# < n.change#

Should give me exactly what I need then, correct?
0
 
LVL 74

Expert Comment

by:sdstuber
ID: 39972866
yes


  the only thing missing from my query was the sorting rule, so I made up my own.

If you have a change# to use for sorting, then, as noted above, use that
0

Featured Post

Webinar: Aligning, Automating, Winning

Join Dan Russo, Senior Manager of Operations Intelligence, for an in-depth discussion on how Dealertrack, leading provider of integrated digital solutions for the automotive industry, transformed their DevOps processes to increase collaboration and move with greater velocity.

Question has a verified solution.

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

This post first appeared at Oracleinaction  (http://oracleinaction.com/undo-and-redo-in-oracle/)by Anju Garg (Myself). I  will demonstrate that undo for DML’s is stored both in undo tablespace and online redo logs. Then, we will analyze the reaso…
Checking the Alert Log in AWS RDS Oracle can be a pain through their user interface.  I made a script to download the Alert Log, look for errors, and email me the trace files.  In this article I'll describe what I did and share my script.
Via a live example, show how to take different types of Oracle backups using RMAN.
This video shows how to recover a database from a user managed backup

726 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