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How do I group the filename coloumn so it is only showing 1 result row per filename?

Posted on 2011-02-22
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Last Modified: 2012-05-11
I need to group the distinct filenames. Currently there is a record for every instance of a filename.
select x.*, (SELECT ratingsum / filenamecount) as divnumber
from (
SELECT  filename, rating,
                          (SELECT     SUM(rating) AS Expr1
                            FROM        mytable AS GV
                            WHERE      GV.filename = a.filename) AS ratingsum,
                          (SELECT     COUNT(*) AS Expr2
                            FROM          mytable AS GV
                            WHERE       GV.filename = a.filename) AS filenamecount
                          
FROM         mytable AS a
) x 
ORDER BY divnumber DESC

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Question by:m2ew
2 Comments
 
LVL 15

Accepted Solution

by:
pateljitu earned 500 total points
ID: 34954790
Group by clause on filename will do the job.

But in this case there is 'rating' is your select statement, if ratings varies you would still get each rows with different 'rating' and same filename. If 'rating' is not required removing from select statement will work.
select x.filename, (SELECT ratingsum / filenamecount) as divnumber
from (
SELECT  filename, rating,
                          (SELECT     SUM(rating) AS Expr1
                            FROM        mytable AS GV
                            WHERE      GV.filename = a.filename) AS ratingsum,
                          (SELECT     COUNT(*) AS Expr2
                            FROM          mytable AS GV
                            WHERE       GV.filename = a.filename) AS filenamecount
                          
FROM         mytable AS a
) x 
group by filename
ORDER BY divnumber DESC

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0
 
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Expert Comment

by:Sharath
ID: 34955912
You can simply do like this.
select filename,sum(rating)*1.0/ count(*) divnumber
  from mytable 
 group by filename
 order by divnumber desc

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In fact, you can use avg function.
select filename,avg(rating) divnumber
  from mytable 
 group by filename
 order by divnumber desc

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