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LINQ Returning Duplicate Results and return a row number.

Posted on 2010-11-17
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Last Modified: 2012-05-10
I am receiving duplicate records with this query... any ideas?
Second question here, I need to know the row number for each record, via a count. Thanks.

      var members = from f in dc.MemberFollowerCounts
                                join m in dc.Members
                                on f.MemberId equals m.MemberId into joinedMemberCount
                                from m in joinedMemberCount.DefaultIfEmpty()
                                orderby f.FollowerCount descending
                                select new
                                {
                                      name = m.Name,
                                      biography = m.Biography,
                                      followers = f.FollowerCount,
                                      profileImageURL = m.ProfileImageURL,
                                      TwitterUserName = m.TwitterUserName.Replace("@",""),
                                      status = m.Status
                                };

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Question by:Rob Gaudet
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13 Comments
 
LVL 25

Expert Comment

by:kevp75
ID: 34163878
It's probably because of your Join.  more than likely there are more than one record in dc.Members that match records in dc.MemberFollowerCounts

for the count, you could add a variable in your loop, and add one each time it iterates
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Author Comment

by:Rob Gaudet
ID: 34164402
Member to MemberFollowerCount is a one to many relationship. Result set incorrectly contains a new row for each record in MemberFollowerCount. I am looking for a single row for each member, that row should also show the highest FollowerCount (int) for each member from the follower count table. I could do this with a sub query in TSQL, not sure how to do this in LINQ.

Member (table)
MemberId
MemberName

MemberFollowerCounts (table)
MemberId
FollowerCount
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LVL 96

Expert Comment

by:Bob Learned
ID: 34166167
It looks like you are doing a Left Join, and not checking to see if "m" is null.
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Author Comment

by:Rob Gaudet
ID: 34183948
I tried a left and right join. To no avail, any LINQ suggestions?
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LVL 25

Expert Comment

by:kevp75
ID: 34187932
can you give us some test data?  I will see if I can get something going
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LVL 96

Expert Comment

by:Bob Learned
ID: 34189262
I agree that it is difficult for you, without knowing your data, to spot any cartesian products, which usually explain duplicate data...
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Author Comment

by:Rob Gaudet
ID: 34310756
I have this issue resolved. Thanks.
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LVL 25

Expert Comment

by:kevp75
ID: 34310875
what did you do to resolve it?
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Author Comment

by:Rob Gaudet
ID: 34310898
I abandoned the initial effort to join the tables. The follower count is now a scalar record in the member table instead of updated in a followercount table.
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Author Comment

by:Rob Gaudet
ID: 34310914
I did have second question here that is pending.

I need to know the rank of the returned row.

Just an off the cuff example, that demonstrates..

from a in stuff
let counter = 0
select new { count = counter++, a.Name };
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Author Comment

by:Rob Gaudet
ID: 34311078
BTW, I solved this as well, I used the Row_Number() function with OVER in SQL and called a stored proc from LINQ instead of LINQ. I would like to know how to increment a row from LINQ though.
-- Region Parameters
DECLARE @p0 Int = 0
DECLARE @p1 Int = 0
DECLARE @p2 NVarChar(1000) = '@'
DECLARE @p3 NVarChar(1000) = ''
-- EndRegion
SELECT ROW_NUMBER() OVER (ORDER BY [Followers] DESC) AS 'RowNumber', [t0].[Name] AS [name], [t0].[Biography] AS [biography], 
    (CASE 
        WHEN [t0].[Followers] IS NULL THEN @p1
        ELSE [t0].[Followers]
     END) AS [followers], [t0].[ProfileImageURL] AS [profileImageURL], REPLACE([t0].[TwitterUserName], @p2, @p3) AS [TwitterUserName], [t0].[Status] AS [status]
FROM [Member] AS [t0]
WHERE ([t0].[UpdatedOn] IS NOT NULL) AND ([t0].[Followers] > @p0) AND (((NOT ([t0].[IsDeleted] = 1)) AND (NOT ([t0].[IsInactive] = 1))) OR (([t0].[IsDeleted] IS NULL) AND ([t0].[IsInactive] IS NULL)))
ORDER BY [t0].[Followers] DESC

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