using System;

using System.Linq; 

using System.Collections;

using System.Collections.Generic;       

using System.Data;

using System.Data.Linq;

using System.Data.DataSetExtensions;

using System.Xml;

using System.IO;

using System.Xml.Linq;

​

public class Program

{

    public static void Main()

    {           

        DataTable myDataTable = new DataTable();

        myDataTable.Columns.Add("userId", typeof(int));

        myDataTable.Columns.Add("createdTime", typeof(DateTime));

        myDataTable.Rows.Add(new object[] {"1",  DateTime.Now.Date.AddDays(2)});

        myDataTable.Rows.Add(new object[] {"4",  DateTime.Now.Date.AddDays(3)});

        myDataTable.Rows.Add(new object[] {"4",  DateTime.Now.Date.AddDays(3).AddMinutes(2)});

        myDataTable.Rows.Add(new object[] {"4",  DateTime.Now.Date.AddDays(3).AddMinutes(1)});

        myDataTable.Rows.Add(new object[] {"1",  DateTime.Now.Date.AddDays(2)});

        myDataTable.Rows.Add(new object[] {"3",  DateTime.Now.Date.AddDays(4)});

        var users =  myDataTable.AsEnumerable()

                .Select(r=> new {

                    UserId = r.Field<int>("UserId"),

                    CreatedTime = r.Field<DateTime>("createdTime")

                }).ToList();

            var groupedUsersResult = from user in users where user.CreatedTime > user.CreatedTime.AddDays(-7) group user by 

                                   new {user.CreatedTime.Year,user.CreatedTime.Month,user.CreatedTime.Day,Minute=(user.CreatedTime.Minute/5),user.UserId}

                                   into groupedUsers select groupedUsers;

            foreach(var groupedUser in groupedUsersResult)

            {

               Console.WriteLine(groupedUser.Key+ " "+ groupedUser.Count());

            }

    }

}

​

​