LINQ TO SQL Limited select statement because of group by

Question

I am looking to find all the dealers in the database that have a duplicate phone number. I then want to list them in a report with all the dealers information. I am having trouble getting my select statement to populate the dealer record attributes.

Such as dealer name address and so fourth. I am thinking it is because of the group by that is limiting it.

var dealers = _db.Dealers
            .Where(x => x.Active)
            .GroupBy(x => x.Phone)
            .Select(x => new { Dealer = x.Key, Phone = x.Count()})
            .Where(x => x.Phone > 1);

Edit: The desired output would be list of each dealer. I want the dealers with the same phone number to appear next to each other. I don't want any records that are not duplicates based on phone number.

Answer 1

Just add the first item in the group to the last Select:

var dealers = _db.Dealers
                 .Where(x => x.Active)
                 .GroupBy(x => x.Phone)
                 .Select(x => new { Dealer = x.Key, Phone = x.Count(), FirstItem = x.First()})
                 .Where(x => x.Phone > 1);

the result will then have a FirstItem property

Or if you want all the items in a flat list you can apply the Where directly to the grouping:

var dealers = _db.Dealers
                 .Where(x => x.Active)
                 .GroupBy(x => x.Phone)
                 .Where(g => g.Count() > 1);
                 .SelectMany(g => g) // flat list of Dealers

Answer 2

You're not saying exactly what the expected output and the actual output is, so I don't know what you mean by 'having trouble'. But I spotted one potentially confusing thing:

You're grouping by the Phone ( .GroupBy(x => x.Phone) ).

So when you do new { Dealer = x.Key, ... the x.Key will refer to the phone number of this group.