how to group by one column only using linq?

Question

I am using a Linq query to group a column (string of Phones) and return that column and the last value of a second column called Status (also a string of numbers). I want to add the result of this query to a new dataTable.

I've tried it in many ways, but the result is always a group of the two columns together and not by one only. If I remove the field status from the dataTable then the group works good, but I need it. Example:

phone status

123 --------- 1

123 --------- 2

I want to retrieve the result: 123, 2 but I get the two rows. Any idea why something like that might happen? This is the code:

var queryGroupLog =
from log2 in lg2.AsEnumerable()
group log2 by log2.Field<string>("Phone") into groupPhone
select groupPhone.OrderBy(p => p.Field<string>("Status")).LastOrDefault();

score 2 · Accepted Answer · answered Aug 02 '15 at 08:18

2

You could try something like this:

var queryGroupLog = from log2 in lg2.AsEnumerable()
                    group log2 by log2.Field<string>("Phone") into groupPhone
                    select new 
                    {
                        Phone = groupPhone.Key,
                        Status = groupPhone.OrderBy(p => p.Field<string>("Status"))
                                           .LastOrDefault()
                    };

answered Aug 02 '15 at 08:18

Christos

53,228
8
76
108

is this equals `groupPhone.Max(...)`? – Grundy Aug 02 '15 at 08:41
@Grundy I think it's the same. However, I haven't tested it. – Christos Aug 02 '15 at 08:43
Thanks, but I'm afraid I'm getting the same result. I'm the checking the result in two ways: 1. foreach (var row in queryGroupLog) { log_grouped.Rows.Add(row); } Console.WriteLine("{0}", log_grouped.Rows.Count); ---------------------------------------------------------------------------------- 2. foreach (var nameGroup in queryGroupLog) {Console.WriteLine("{0}", b); b++; } ----------------------------------------------------------------------I'm getting the number of a result of a group by both columns. – Talkat Aug 02 '15 at 10:37
Found the problem! and used the answer above also. Thanks again! :) – Talkat Aug 02 '15 at 15:12

score -1 · Answer 2 · edited Jan 10 '18 at 13:40

-1

new KeyValuePair(groupPhone.Key,groupPhone.OrderBy((p) => p.Field("Status")).LastOrDefault()))

edited Jan 10 '18 at 13:40

Soner Gönül

97,193
102
206
364

answered Aug 02 '15 at 08:17

Thaina Yu

1,372
2
16
27

how to group by one column only using linq?

phone status

2 Answers2