Solved

Sum Function Workaround?

Posted on 2013-10-24
5
242 Views
Last Modified: 2013-10-28
Hello:

I have a Data table that looks like this:
ID      PersonName      PersonClass
557      Dan      P
557      Dan      S
557      Dan      S
557      Dan      P
557      Dan      S
557      Dan      S
189      Mike      S
189      Mike      S
189      Mike      S

What I want to do is if there is a P in the PersonClass Column then Y if not N. My output will look like this

ID      PERSONNAME      PC
557      Dan      Y
189      Mike      N

Here is the script that I am using. It works, however, one of the tables has over 600,000 entries and the sum function really slows it down. Is there a way to a achieve my result without using sum or count?

SELECT ID, PERSONNAME, CASE WHEN PC >=1 THEN 'Y' ELSE 'N' END AS PC
FROM
(
SELECT ID, PERSONNAME, SUM(PC) AS PC
FROM
(
select ID, PERSONNAME, case when PERSONCLASS = 'p' THEN 1 ELSE 0 END AS PC FROM Test
)
table1
GROUP BY ID, PERSONNAME
)
TABLE2

Open in new window

0
Comment
Question by:RecipeDan
5 Comments
 
LVL 39

Expert Comment

by:lcohan
ID: 39598821
Did you tried simple CASE statement like:



select ID, PERSONNAME, case when PERSONCLASS = 'p' THEN 1 ELSE 0 END AS PC FROM Test
GROUP BY PERSONNAME
0
 
LVL 16

Expert Comment

by:DcpKing
ID: 39598823
select PersonClass, count(PersonClass) 
from table 
group by PersonClass

Open in new window

will give you how many P's and how many S's overall.

Then expand that to individuals
select PersonName, PersonClass, count(PersonClass) 
from table 
group by PersonName, PersonClass

Open in new window

to get the name, class, and count.

Even with a million records it shouldn't take _that_ long, but I doubt that there's a better way.
0
 
LVL 21

Accepted Solution

by:
Dale Burrell earned 500 total points
ID: 39598824
Its unlikely to be the 'sum' which is an issue... 600000 records isn't many in the great database scheme of things.

It could be the fact that you have 3 nested queries which might be preventing the optimiser from working. Or it could be the lack of a good index.

I recon this, simplified, query will produce the same result - don't know if it is faster though.

select id, PersonName, max(case when PERSONCLASS = 'p' THEN 'Y' ELSE 'n') END
from Test
group by id, PersonName

Open in new window

0
 
LVL 39

Expert Comment

by:lcohan
ID: 39598830
Sorry I missed the ID in the group by:

select ID, PERSONNAME, case when PERSONCLASS = 'p' THEN 1 ELSE 0 END AS PC FROM Test
GROUP BY ID, PERSONNAME
0
 
LVL 48

Expert Comment

by:PortletPaul
ID: 39599425
As P < S  I would just go for a simple MIN(PERSONCLASS) and then do a case expression on that - you do fewer case expressions this way.
|  ID | PERSONNAME | PC |
|-----|------------|----|
| 557 |        Dan |  Y |
| 189 |       Mike |  N |


SELECT
        id
      , PersonName
      , CASE WHEN MIN(PERSONCLASS) = 'P' THEN 'Y' ELSE 'N' END as PC
FROM YourTable
GROUP BY id
       , PersonName
;   
    
    CREATE TABLE YourTable
    	([ID] int, [PersonName] varchar(4), [PersonClass] varchar(1))
    ;
    	
    INSERT INTO YourTable
    	([ID], [PersonName], [PersonClass])
    VALUES
    	(557, 'Dan', 'P'),
    	(557, 'Dan', 'S'),
    	(557, 'Dan', 'S'),
    	(557, 'Dan', 'P'),
    	(557, 'Dan', 'S'),
    	(557, 'Dan', 'S'),
    	(189, 'Mike', 'S'),
    	(189, 'Mike', 'S'),
    	(189, 'Mike', 'S')
        ;
        
http://sqlfiddle.com/#!3/15ef6/4 

Open in new window

If you still have performance issues please provide an execution plan (as .sqlplan file)
0

Featured Post

Is Your Active Directory as Secure as You Think?

More than 75% of all records are compromised because of the loss or theft of a privileged credential. Experts have been exploring Active Directory infrastructure to identify key threats and establish best practices for keeping data safe. Attend this month’s webinar to learn more.

Question has a verified solution.

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

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.
In this article we will get to know that how can we recover deleted data if it happens accidently. We really can recover deleted rows if we know the time when data is deleted by using the transaction log.
This video shows, step by step, how to configure Oracle Heterogeneous Services via the Generic Gateway Agent in order to make a connection from an Oracle session and access a remote SQL Server database table.
Using examples as well as descriptions, and references to Books Online, show the documentation available for datatypes, explain the available data types and show how data can be passed into and out of variables.

943 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

Need Help in Real-Time?

Connect with top rated Experts

10 Experts available now in Live!

Get 1:1 Help Now