Concatenate many rows into a single text string in Entity framework

Question

Consider a database table holding names, with three rows:

SubjectID      StudentName
---------      -------------
 1             Peter
 2             Paul
 2             Mary

Is there an easy way to turn this into a single string in entity framework? something like this:

SubjectID       StudentName
----------      -------------
1               Peter
2               Paul, Mary

Check this link to more information.

1) what have you tried? 2) the inputs/outputs don't match! 3) your output example is arbitrary. what's the logic? — Grant Thomas, May 28 '13 at 12:33
please check http://stackoverflow.com/questions/194852/concatenate-many-rows-into-a-single-text-string for more info — Hossein Moradinia, May 28 '13 at 12:35
Your example output still defies your request. _What do you want, and where are you stuck with it?_ — Grant Thomas, May 28 '13 at 12:41
@HosseinMoradinia Shouldn't it be Paul, Marry against SubjectID 2 in your example? — Khadim Ali, May 28 '13 at 13:23

Dave New · Accepted Answer · 2013-05-28T13:21:21.193

7

You can use GroupBy to group your students by subject:

var result = StudentSubjects
                .GroupBy(x => x.SubjectID)
                .Select(x => new 
                    { 
                        Subject = x.Key, 
                        Names = String.Join(", ", x.Select(n => n.Name)) 
                    });

I have used String.Join to concatenate the list of names.

edited May 28 '13 at 13:21

answered May 28 '13 at 12:45

Dave New

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I got error LINQ to Entities does not recognize the method 'System.String Join – Moayad Myro Apr 04 '18 at 12:20

Concatenate many rows into a single text string in Entity framework

1 Answers1