Solved

% change between rows

Posted on 2002-04-12
6
275 Views
Last Modified: 2006-11-17
I want to get something like the following.

week count % changed
10   100     0
11   200     100%
12   300     50%
13   100     -66.7%
14   500     500%


What's the simplest way to do this?
0
Comment
Question by:gotaquestion
[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
  • 2
6 Comments
 
LVL 69

Expert Comment

by:Scott Pletcher
ID: 6937407
Perhaps something like this:

SELECT week, [count],
    (SELECT ISNULL(CAST((currwk.[count] - prevwk.[count]) AS DECIMAL(10,2)) /
            CAST(currwk.[count] AS DECIMAL(10,2)) * 100.00,0) AS '% changed'
     FROM tablename prevwk
     WHERE prevwk.week = currwk.week - 1)
FROM tablename currwk
0
 
LVL 5

Expert Comment

by:spcmnspff
ID: 6937423
This will find the percentage change in records. in a table provided there is a column named week.  Change Column1 to the name of any field in the table other than Week.

SET ARITHABORT OFF
Select [Week], C1 [Count], (C1-C2)/C1 [% Change]
From
     (select T1.[Week], Count(T1.Column1) C1,
         (Select IsNull(Count(T2.Column1) from MyTable T2 Where T2.[Week] = T1.[Week]-1),0) C2
     From MyTable T1
     Group By T1.[Week]) VT


If you don't have a week field, then you can use the datepart function to get the date from a create date:


SET ARITHABORT OFF
Select [Week], C1 [Count], (C1-C2)/C2 [% Change]
From
     (select DatePart(wk,T1.CreateDt) [Week],
         Count(T1.Column1) C1,
         (Select IsNull(Count(T2.Column1)
             from MyTable T2
             Where DatePart(wk,T2.CreateDt) =
                 DatePart(wk,T1.CreateDt)-1),0) C2
      From MyTable T1
      Group By DatePart(wk,T1.CreateDt)-1)) VT


0
 
LVL 5

Expert Comment

by:spcmnspff
ID: 6937435
Minor Change:  Had to divide by C2 rather than C1:

SET ARITHABORT OFF
Select [Week], C1 [Count], (C1-C2)/C2 [% Change]
From
    (select T1.[Week], Count(T1.Column1) C1,
        (Select IsNull(Count(T2.Column1) from MyTable T2 Where T2.[Week] = T1.[Week]-1),0) C2
    From MyTable T1
    Group By T1.[Week]) VT


Or with the datepart function:

SET ARITHABORT OFF
Select [Week], C1 [Count], (C1-C2)/C2 [% Change]
From
    (select DatePart(wk,T1.CreateDt) [Week],
        Count(T1.Column1) C1,
        (Select IsNull(Count(T2.Column1)
            from MyTable T2
            Where DatePart(wk,T2.CreateDt) =
                DatePart(wk,T1.CreateDt)-1),0) C2
     From MyTable T1
     Group By DatePart(wk,T1.CreateDt)-1)) VT
0
Major Incident Management Communications

Major incidents and IT service outages cost companies millions. Often the solution to minimizing damage is automated communication. Find out more in our Major Incident Management Communications infographic.

 
LVL 1

Author Comment

by:gotaquestion
ID: 6937507
I've created a table to support your queries and with both the last ones your proposed I'm getting.  

Server: Msg 156, Level 15, State 1, Line 7
Incorrect syntax near the keyword 'from'.

I think it's missing a )

I can't seem to see it.


0
 
LVL 5

Accepted Solution

by:
spcmnspff earned 100 total points
ID: 6937548
Oops.  Fixed it.  I had to change the  postition of my isnull =)  :

SET ARITHABORT OFF
Select [Week], C1 [Count], (C1-C2)/C2 [% Change]
From
   (select T1.[Week], Count(T1.Column1) C1,
       IsNull((Select Count(T2.Column1) from MyTable T2 Where T2.[Week] = T1.[Week]-1),0) C2
   From MyTable T1
   Group By T1.[Week]) VT


Or with the datepart function:

SET ARITHABORT OFF
Select [Week], C1 [Count], (C1-C2)/C2 [% Change]
From
   (select DatePart(wk,T1.CreateDt) [Week],
       Count(T1.Column1) C1,
       IsNull((Select Count(T2.Column1)
           from MyTable T2
           Where DatePart(wk,T2.CreateDt) =
               DatePart(wk,T1.CreateDt)-1),0) C2
    From MyTable T1
    Group By DatePart(wk,T1.CreateDt)) VT
0
 
LVL 1

Author Comment

by:gotaquestion
ID: 6937619
Thanks, I had to fix the divide by zero error because the
SET ARITHIGNORE OFF
SET ARITHABORT OFF
were not working for some reason.

Select [Week], C1 [Count], CASE C2 WHEN 0 THEN 0 ELSE (C1-C2)/C2 END [% Change]
From
  (select T1.[Week], sum(T1.Column1) C1,
      IsNull((Select sum(T2.Column1) from MyTable T2 Where T2.[Week] = T1.[Week]-1),0) C2
  From MyTable T1
  Group By T1.[Week]) VT
0

Featured Post

Forrester Webinar: xMatters Delivers 261% ROI

Guest speaker Dean Davison, Forrester Principal Consultant, explains how a Fortune 500 communication company using xMatters found these results: Achieved a 261% ROI, Experienced $753,280 in net present value benefits over 3 years and Reduced MTTR by 91% for tier 1 incidents.

Question has a verified solution.

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

Everyone has problem when going to load data into Data warehouse (EDW). They all need to confirm that data quality is good but they don't no how to proceed. Microsoft has provided new task within SSIS 2008 called "Data Profiler Task". It solve th…
Load balancing is the method of dividing the total amount of work performed by one computer between two or more computers. Its aim is to get more work done in the same amount of time, ensuring that all the users get served faster.
Using examples as well as descriptions, and references to Books Online, show the documentation available for date manipulation functions and by using a select few of these functions, show how date based data can be manipulated with these functions.
Viewers will learn how to use the SELECT statement in SQL to return specific rows and columns, with various degrees of sorting and limits in place.

729 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