Solved

How do I select the first row from each subset of data within a query result?

Posted on 2010-08-27
5
398 Views
Last Modified: 2013-11-05
Hi!

I've got a MS SQL 2000 query that produces the following result:

Schedule    Date         Class          Period               Count       
----------- ------------ -------------- -------------------- ----------- 
441         2008/07/28   DEVL 101       A3201                205 
441         2008/07/28   DEVL 101       ZR019                102
 ...
441         2008/07/28   DEVL 101       BF012                1
554         2009/02/14   DEVL 154       X5002                384 
554         2009/02/14   DEVL 154       W8098                98
 ...
554         2009/02/14   DEVL 154       H2309                5

Open in new window


From this query, I want to select the Schedule, Date, Class, and Period with the highest Count from the rows that contain the same values for Schedule, Date, and Class.

The result should look like this:

Schedule    Date         Class          Period               Count       
----------- ------------ -------------- -------------------- ----------- 
441         2008/07/28   DEVL 101       A3201                205 
554         2009/02/14   DEVL 154       X5002                384
 ...

Open in new window


0
Comment
Question by:PaulELS
[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
5 Comments
 
LVL 2

Expert Comment

by:SkydiverFL
ID: 33544206
SELEC TOP 1 FROM...
0
 
LVL 92

Accepted Solution

by:
Patrick Matthews earned 500 total points
ID: 33544233
SELECT t1.Schedule, t1.Date, t1.Class, t1.Period, t1.[Count]FROM SomeTable t1 INNER JOIN    (SELECT t2.Schedule, t2.Date, t2.Class, MAX(t2.[Count]) AS MaxCount    FROM SomeTable    GROUP BY t2.Schedule, t2.Date, t2.Class) x ON t1.Schedule = x.Schedule AND t1.Date = x.Date AND t1.Class = x.Class AND t1.[Count] = x.MaxCount
0
 
LVL 25

Expert Comment

by:jrb1
ID: 33544249
one way to do it (my preferred method)

select Schedule, Date, Class, Period, Count
from yourtable A
where count = (select max(count) from yourtable
                 where schedule = a.schedule
                 and date = a.date
                 and class = a.class
                and period = a.period)
0
 
LVL 2

Author Comment

by:PaulELS
ID: 33544345
Thanks, matthewspatrick!
0
 
LVL 8

Expert Comment

by:Mohit Vijay
ID: 33544502
In Below query, you need to change Table1 with your table name.

SELECT tbl.Schedule, tbl.Date, tbl.Class, tbl.Period, t1.[Count]
FROM (SELECT Schedule, Date, Class, MAX(Count) AS MaxCount
   FROM Table1
   GROUP BY Schedule, Date, Class) AS tbl2 LEFT OUTER JOIN Table1 tbl 
  ON tbl2.Schedule = tbl.Schedule AND tbl2.Date = tbl.Date AND tbl2.Class = tbl.Class AND tbl.Count= tbl2.MaxCount

Open in new window

0

Featured Post

Free Tool: ZipGrep

ZipGrep is a utility that can list and search zip (.war, .ear, .jar, etc) archives for text patterns, without the need to extract the archive's contents.

One of a set of tools we're offering as a way to say thank you for being a part of the community.

Question has a verified solution.

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

How to leverage one TLS certificate to encrypt Microsoft SQL traffic and Remote Desktop Services, versus creating multiple tickets for the same server.
International Data Corporation (IDC) prognosticates that before the current the year gets over disbursing on IT framework products to be sent in cloud environs will be $37.1B.
Via a live example, show how to backup a database, simulate a failure backup the tail of the database transaction log and perform the restore.
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.

691 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