Solved

Get the Sum of a count of a group

Posted on 2008-10-28
14
233 Views
Last Modified: 2010-04-21
Given the following Table:
Student  LessonID    TotalNumLessonsInSyllabus
--------------------------------------------------
Student1    C001               8
Student1    C002               8
Student1    X063               8
Student1    X054                     8
Student2    C004               8
Student2    X054               8
Student2    X056               8
Student3    X063                8
Student3    C004               8
Student3    X054               8
Student3    X056               8


How do I get a total number of LessonID per student.
In this example Student1 = 4; Student2 = 04 and Student3 = 3

Bonus for giving me the count of LessonIDs starting with X and count of Lessons starting with C


select Student,  LessonID, @SumOfTotalLessons as TotalNumberOfLessonsInSyllabus
from	  #CompletedCBTS 
group by LessonID, Student
order by student , LessonID

Open in new window

0
Comment
Question by:rhat
[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
  • 3
  • 2
  • +3
14 Comments
 
LVL 60

Assisted Solution

by:chapmandew
chapmandew earned 62 total points
ID: 22824958
select Student,  LessonID, count(*) as TotalNumberOfLessonsInSyllabus
from      #CompletedCBTS
group by LessonID, Student
0
 
LVL 39

Assisted Solution

by:BrandonGalderisi
BrandonGalderisi earned 62 total points
ID: 22825065
Try this


select sutdent
,sum(TotalNumLessonsInSyllabus)
,sum(case when left(lessonid)='C' then 1 else 0 end) as C_Count
,sum(case when left(lessonid)='X' then 1 else 0 end) as X_Count
,count(*) as Lesson_Count
from #completedCBTs
group by studentID

0
 
LVL 9

Assisted Solution

by:jamesgu
jamesgu earned 62 total points
ID: 22825070
select Student,  LessonID, count(*) as TotalNumberOfLessonsInSyllabus
, count( case when Left(LessonID, 1)='X' then 1 else 0 end ) as number_of_X_lessons
, count( case when Left(LessonID, 1)='C' then 1 else 0 end ) as number_of_C_lessons
from      #CompletedCBTS
group by Student , LessonID
0
Comparison of Amazon Drive, Google Drive, OneDrive

What is Best for Backup: Amazon Drive, Google Drive or MS OneDrive? In this free whitepaper we look at their performance, pricing, and platform availability to help you decide which cloud drive is right for your situation. Download and read the results of our testing for free!

 
LVL 60

Assisted Solution

by:Kevin Cross
Kevin Cross earned 62 total points
ID: 22825071
Chapman's answer is correct, so I will go for the bonus.
select Student,  LessonID
, SUM(CASE LEFT(LessionID,1) WHEN 'X' THEN 1 ELSE 0 END) as TotalNumberOfLessonsInSyllabusX
, SUM(CASE LEFT(LessionID,1) WHEN 'C' THEN 1 ELSE 0 END) as TotalNumberOfLessonsInSyllabusC
from      #CompletedCBTS 
group by LessonID, Student

Open in new window

0
 
LVL 60

Expert Comment

by:Kevin Cross
ID: 22825078
Oh, two slow although, I think you want SUM jamesqu and Brandon's needs the LEFT(..., 1) but is correct.
0
 
LVL 60

Expert Comment

by:Kevin Cross
ID: 22825113
Think COUNT works jamesqu when the ELSE is NULL as the aggregate will optimize it out of the count.  Just out of habit always use the SUM as usually I put 1 or 0 and count will count the 0 as an occurrence where as sum will add up values and thus only grabbing the 1's.

This may work:
COUNT(case when Left(LessonID, 1)='C' then 1 end)
OR
COUNT(case when Left(LessonID, 1)='C' then 1 else NULL end)
0
 
LVL 39

Expert Comment

by:BrandonGalderisi
ID: 22825179
0
 
LVL 3

Accepted Solution

by:
TechSinger earned 252 total points
ID: 22825275
All the exmples I am seing are actually showing LessonID, but I got the impression that you wanted a count of LessonID for each student.  I could probably work on the bonus for you too by using the UNION command.
Here is the code I would use.

SELECT T1.Student,'C' AS [Lesson Type],
COUNT(T1.LessonID) AS [Lesson Count]
FROM #CompletedCBTS T1
WHERE LEFT(T1.LessonID,1)='C' 
UNION
SELECT T2.Student,'X' AS [Lesson Type],
COUNT(T2.LessonID) AS [Lesson Count]
FROM #CompletedCBTS T2
WHERE LEFT(T2.LessonID,1)='X' 
ORDER BY [Lesson Count] DESC

Open in new window

0
 
LVL 60

Expert Comment

by:Kevin Cross
ID: 22826391
Lol, copied that without looking.  Talk about doh!
0
 
LVL 60

Expert Comment

by:Kevin Cross
ID: 22826401

select Student
, SUM(CASE LEFT(LessionID,1) WHEN 'X' THEN 1 ELSE 0 END) as TotalNumberOfLessonsInSyllabusX
, SUM(CASE LEFT(LessionID,1) WHEN 'C' THEN 1 ELSE 0 END) as TotalNumberOfLessonsInSyllabusC
from      #CompletedCBTS 
group by Student

Open in new window

0
 

Author Comment

by:rhat
ID: 22826444
Feast or famine looks like.  :)

This is what I came up with in the mean time

 SELECT
    Student, Squadron,
    COUNT(*) AS TotalCBTsCompletedPerStudent, (select case when count(Right(LessonID,3)) > =  @CountOfRegCBTs then 'Complete' else 'Incomplete' end) as Complete, @CountOfRegCBTs as RegCBTsInSyllabus,  @CountOfTestOuts as TestOutsInSyllabus
FROM #CompletedCBTs

I haven't worked TechSinger's solution into it yet (but I will).  TS your code required adding a group by in both sections.

TechSinger I think is the closest and I will award him 250 points and split the remaining among the other 4.
Any fast rules of thumb for aggregates and group by?

Thanks Guys.

mwvisa1: got the bonus I think.
0
 

Author Closing Comment

by:rhat
ID: 31510891
Thanks Guys.
0
 
LVL 3

Expert Comment

by:TechSinger
ID: 22827284
Your right rhat.  I left out the Group By's.  Since I don't have any real tables like what you have, I was only able to check the Syntax and I didn't get any error.  I'm sure I would have gotten some errors if I would have tried to execute it.
Thanks for the points.
0
 
LVL 39

Expert Comment

by:BrandonGalderisi
ID: 22827335
Also, there is no reason for this:

case when count(Right(LessonID,3)) > =  @CountOfRegCBTs then 'Complete' else 'Incomplete' end

Now if you wanted to do a distinct right, that's fine.  But counting a right() is an unnecessary string manipulation.

case when count(distinct Right(LessonID,3)) > =  @CountOfRegCBTs then 'Complete' else 'Incomplete' end
0

Featured Post

Raise the IQ of Your IT Alerts

From IT major incidents to manufacturing line slowdowns, every business process generates insights that need to reach the people required to take action. You need a platform that integrates with your business tools to create fully enabled DevOps toolchains.

You need xMatters.

Question has a verified solution.

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

JSON is being used more and more, besides XML, and you surely wanted to parse the data out into SQL instead of doing it in some Javascript. The below function in SQL Server can do the job for you, returning a quick table with the parsed data.
Ever wondered why sometimes your SQL Server is slow or unresponsive with connections spiking up but by the time you go in, all is well? The following article will show you how to install and configure a SQL job that will send you email alerts includ…
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 the fundamental information of how to create a table.

689 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