Please Help me to take Top 10 Distinct Rows order by Date

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Hi,

I have a Datatable having records like this...

JID                      Date                     RecentChatString
-----------------------------------------------------------------------
abc@gmail.com         11/Nov/2013 11:53:00        Hi
abc@gmail.com         11/Nov/2013 11:53:10        Hello
abc@gmail.com         11/Nov/2013 11:54:00        Good Morning
def@gmail.com         11/Nov/2013 12:03:00        Ok
abc@gmail.com         11/Nov/2013 12:05:10        Please reply
def@gmail.com         11/Nov/2013 12:15:00        Good after noon
def@gmail.com         11/Nov/2013 12:15:50        Ok bye

I want to get Top 10 Distinct Records sorted by Date and, Means only the recent chat of each JID..

JID                      Date                     RecentChatString
-----------------------------------------------------------------------
abc@gmail.com         11/Nov/2013 12:05:10        Please reply
def@gmail.com         11/Nov/2013 12:15:50        Ok bye

Now I have a code like this... I can get the top 10 records sorted by date using this code...
But, It contains duplicate JID's.... Please help me .... (recent_index is a DataTable)

C#

 DataRow recent_dr = recent_index.NewRow();
 recent_dr["JID"] = RosterId;
 recent_dr["Date"] = DateTime.Now;
 recent_dr["RecentChatString"] = _chatline;
 recent_index.Rows.Add(recent_dr);

 DataTable dtt = new DataTable("RecentChats");
  dtt.Columns.Add("JID", Type.GetType("System.String"));
 dtt.Columns.Add("Date", Type.GetType("System.DateTime"));
 dtt.Columns.Add("RecentChatString", Type.GetType("System.String"));

 IEnumerable<DataRow> recentTen = recent_index.AsEnumerable().OrderByDescending(x=>x["Date"]).Take(10);
recentTen.CopyToDataTable(dtt, LoadOption.OverwriteChanges);

 dtt.WriteXml(s + "\\FPhoneData\\chats\\index.xml");

Posted 20-Nov-13 22:34pm

Yesudasan Moses

Updated 20-Nov-13 22:35pm

v2

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2 solutions

Solution 1

Include Distinct() at the end and check.

C#

IEnumerable<datarow> recentTen = GetTable().AsEnumerable().OrderByDescending(x => x["Date"]).Take(10).Distinct();

Posted 20-Nov-13 22:50pm

Thomas ktg

Updated 20-Nov-13 22:51pm

v2

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Er Daljeet Singh · Accepted Answer · 2013-11-21T00:52:00

Here is the solution for your query

here i am creating a DataTable

DataTable dt = new DataTable("mytable");
      DataColumn dc1 = new DataColumn("ID", typeof(int));
      dc1.AutoIncrement = true;
      dc1.AutoIncrementSeed = 1;
      dc1.AutoIncrementStep = 1;
      dt.Columns.Add(dc1);
      dt.Columns.Add(new DataColumn("name", typeof(string)));
      dt.Columns.Add(new DataColumn("age", typeof(string)));
      dt.Columns.Add(new DataColumn("date", typeof(DateTime)));

      for (int i = 0; i < 10; i++)
      {
          DataRow dr = dt.NewRow();
          dr["name"] = "dasda " + i.ToString();
          dr["age"] = (i * i).ToString();

          switch (i)
          {
              case 0: dr["date"] = DateTime.Now.AddDays(i);
                  break;
              case 1: dr["date"] = DateTime.Now.AddDays(2);
                  break;
              case 2: dr["date"] = DateTime.Now.AddDays(i * i);
                  break;
              case 3: dr["date"] = DateTime.Now.AddDays(i * i);
                  break;
              case 4: dr["date"] = DateTime.Now.AddDays(2);
                  break;
              case 5: dr["date"] = DateTime.Now.AddDays(i * i);
                  break;
              case 6: dr["date"] = DateTime.Now.AddDays(2);
                  break;
              case 7: dr["date"] = DateTime.Now.AddDays(i * i);
                  break;
              case 8: dr["date"] = DateTime.Now.AddDays(i * i);
                  break;
              case 9: dr["date"] = DateTime.Now.AddDays(2);
                  break;
              default:
                  break;
          }
          dt.Rows.Add(dr);

      }

now i am firing the LINQ query to fetch the records as you want..

XML

var xyz = (from m in dt.Select()
                  let _name = m.Field<string>("name")
                  let _date = m.Field<DateTime>("date")
                  let _age = m.Field<string>("age")
                  let _id = m.Field<int>("id")
                  orderby _date descending
                  group m by _date into g
                  select new
                  {
                      _name = g.First()["name"].ToString(),
                      _id = Convert.ToInt32(g.First()["ID"]),
                      _age = g.First()["age"].ToString(),                     
                      _date = (DateTime)g.First()["date"]                     
                  }).ToList();

this query will give the distinct record on the behalf of date.for fetching last ten record i used order by descending.
you want top 10 record then simply call TAKE() you wiil get the result.

var res= xyz.Take(10);

you will get the top 10 records.