.NET Merge Single Column from datarows when ID matchs - asp.net

Question

Just in advance, I have no access to the SQL query written, so all I can do is try to handle the dataset after the query has executed.
I'm using ASP.NET Webforms to try and merge only one column across a SQL returned datatable e.g
PID | C1 | C2 | C3 | I1
1 | a | a | a | bob
1 | x | x | x | Jim
1 | b | b | b | Fred
2 | g | g | g | Jill
From this Dataset I would like to see:
PID | C1 | C2 | C3 | I1
1 | a | a | a | bob Jim Fred
2 | g | g | g | Jill
Essentially I don't care what is in C1-C3, it will just take the values of the first match. What I need to do though is join all the values of I1 into the one result based on a matching PID.
Any help would be greatly appreciated. LINQ answers acceptable, preferably in vb.net so I don't have to change it later.
Thank you.

Answer 1

You can use the group by with the String.Join. Ia,m adding answer in c# you might want to convert to vb(I not very well with vb syntax :P).
var result = dataListObject.GroupBy(l => l.PId )
.Select(g => new { PID = g.Key.PId, C1= g.Key.C1, C2 = g.Key.C2, C3=g.Key.C3, I1 = string.Join(",", g.Select(i => i.I1)) });
Should select the first PID, C1 ,C2 and C3. Then join the I1 together. Haven't checked this but seems like it should work.
UPDATE
For datatable you can apply the AsEnumerable() to datatable to make it enumerable
var result = datatable.AsEnumerable().GrouBy(l=>l.Field<string>("Pid"))
.Select(g=>new{PID = g.Key.PId, C1= g.Key.C1, C2 = g.Key.C2, C3=g.Key.C3, I1 = string.Join(",", g.Select(i => i.I1)) });