How to summarize data with MSSQL

Posted on 2012-03-29
Medium Priority
Last Modified: 2012-03-29
Hello Experts,

I am having trouble creating a query that will summarize data from a few tables that store sent fax history... Here's the basic query:

FROM documents doc
JOIN history hist ON hist.id = doc.docid
JOIN historydetails hd ON hd.id = hist.id

The documents table contains all documents to be sent. Table historydetails has a row for each document being sent out. So, if a document was sent without any errors, there will only be one row in historydetails per document. Now, if there were errors, more than one row in historydetails will be associated with documents. Column status in historydetails determines if an error has been sent. If status equals 5, document was sent successfully. Also, pages indicates number of pages sent out. So for example,

ID     Status    Pages
1       3            4
1       1            2
1       5            6
2       5            8
3       4            0
3       1            0
3       6            1

This table shows that document ID 1 had three attempts, 2 failed, 1 was successful, and in total 10 pages were sent. Document ID 2 had 1 successfull attempt, 8 pages sent. Document ID 3 has 3 attempts, none successful, 1 page sent. What I would like to do, is summarize the data into something like this:

Documents ID           Attempts   Failed      Successful Pages
1                                3                2             1               10
2                                1                0             1                8
3                                3                3             0                1

I appreciate any help provided... Thanks.
Question by:horalia
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LVL 60

Accepted Solution

Kevin Cross earned 2000 total points
ID: 37783168

You can use conditional aggregation to achieve this.

SELECT [Document ID] = doc.docid
     , Attempts = COUNT(*)
     , Failed = SUM(CASE hd.Status WHEN 5 THEN 0 ELSE 1 END)
     , Successful = COUNT(CASE hd.Status WHEN 5 THEN 1 END)
     , Pages = SUM(hd.Pages)
FROM documents doc
JOIN history hist ON hist.id = doc.docid
JOIN historydetails hd ON hd.id = hist.id
GROUP BY doc.docid

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EDIT: ensure to correctly identify which table each column is coming from.

Expert Comment

ID: 37783245
document ID 1 had three attempts, 2 failed, 1 was successful, and in total 10 pages were sent.
ID     Status    Pages
1       3            4
1       1            2
1       5            6
How did you come up with 10 pages?

One possible answer to the problem (assuming that you wanted 12 pages for ID 1, not 10) is to build multiple temp tables in your query and do left joins to return a full set.

Given the following tables...
docid	docname
1	doc1
2	doc2
3	doc3

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id	historydata
3	hist3
2	hist2
1	hist1

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id	status	pages
1	3	4
1	1	2
1	5	6
2	5	8
3	4	0
3	1	0
3	6	1

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Try the following...
SELECT doc.docid, doc.docname, hist.historydata, hd1.attempts, hd2.failed, hd3.successful, hd4.pages
FROM documents doc
JOIN history hist ON hist.id = doc.docid
left JOIN (select id, count(*) as attempts from historydetails group by id) hd1 ON hd1.id = doc.docid
left JOIN (select id, count(status) as failed from historydetails where status!=5 group by id) hd2 ON hd2.id = doc.docid
left JOIN (select id, count(status) as successful from historydetails where status=5 group by id) hd3 ON hd3.id = doc.docid
left JOIN (select id, sum(pages) as pages from historydetails group by id) hd4 ON hd4.id = doc.docid

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...returns this...
docid	docname	historydata  attempts  failed	successful  pages
1	doc1	hist1	    3	    2	1	  12
2	doc2	hist2	    1	    NULL	1	  8
3	doc3	hist3	    3	    3	NULL	  1

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Author Closing Comment

ID: 37783312
Worked great. Thanks!
LVL 57

Expert Comment

ID: 37783350
here it is:

with s as (
select 1 id, 3 status, 4 pages
union all select 1,1,2
union all select 1,5,6
union all select 2,5,8
union all select 3,4,0
union all select 3,1,0
union all select 3,6,1
select id, COUNT(1) attempt, 
  SUM (case when status!=5 then 1 else 0 end) Failed,
  SUM (case when status=5 then 1 else 0 end) Successful,
  SUM (Pages) Pages
from s
group by id
order by id

id	attempt	Failed	Successful	Pages
1	3	2	1	12
2	1	0	1	8
3	3	3	0	1

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there is a issue with pages, I guess you calculated wrong!

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