using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

       List<ProjectResult> result = new List<ProjectResult> {  

            new ProjectResult { Name = "Project 1", MonthYear = "2020-08", LiveDate = Convert.ToDateTime("2020-08-28 00:00:00.000") },  

            new ProjectResult { Name = "Project 2", MonthYear = "2020-08", LiveDate = Convert.ToDateTime("2020-08-27 00:00:00.000") },  

            new ProjectResult { Name = "Project 3", MonthYear = "2020-08", LiveDate = Convert.ToDateTime("2020-08-26 00:00:00.000") },  

            new ProjectResult { Name = "Project 4", MonthYear = "2021-08", LiveDate = Convert.ToDateTime("2020-08-28 00:00:00.000") },  

            new ProjectResult { Name = "Project 5", MonthYear = "2021-08", LiveDate = Convert.ToDateTime("2020-08-27 00:00:00.000") },  

            new ProjectResult { Name = "Project 6", MonthYear = "2021-08", LiveDate = Convert.ToDateTime("2020-08-26 00:00:00.000") },

       };

       int augRow = 1;

       int sepRow = 1;

       var queryAug = result.Where(c => c.LiveDate != Convert.ToDateTime("1900-01-01 00:00:00.000") && c.LiveDate.Month == 8)

              .GroupBy(c => new { c.MonthYear, c.Name})

              .Select(g => new DynamicProjectCalendarAug

              {

                  GroupRowId = augRow++,

                  MonthYear = g.Key.MonthYear,

                  ProjectName = g.Key.Name,

                  Aug = g.Where(c => c.LiveDate != Convert.ToDateTime("1900-01-01 00:00:00.000") && c.LiveDate.Month == 8).Max(c => c.Name)

              }).ToList();

        var querySep = result.Where(c => c.LiveDate != Convert.ToDateTime("1900-01-01 00:00:00.000") && c.LiveDate.Month == 9)

                  .GroupBy(c => new { c.MonthYear, c.Name})

                  .Select(g => new DynamicProjectCalendarSep

                  {

                      GroupRowId = sepRow++,

                      MonthYear = g.Key.MonthYear,

                      ProjectName = g.Key.Name,

                      Sep = g.Where(c => c.LiveDate != Convert.ToDateTime("1900-01-01 00:00:00.000") && c.LiveDate.Month == 9).Max(c => c.Name)

                  }).ToList();

        List<object> query = queryAug.Cast<object>()

                    .Concat(querySep).ToList();

        foreach(var item in queryAug)

        {

            Console.WriteLine("GroupRowId: {0}, MonthYear: {1}, ProjectName: {2}", item.GroupRowId, item.MonthYear, item.ProjectName);

        }

    }

​

    public class ProjectResult

    {

        public string MonthYear { get; set; }

        public string Name { get; set; }

        public DateTime LiveDate { get; set; }

    }

    public class DynamicProjectCalendarAug

    {

        public int GroupRowId { get; set; }

        public string MonthYear { get; set; }

        public string ProjectName { get; set; }

        public string Aug { get; set; }

    }

​

    public class DynamicProjectCalendarSep

    {

        public int GroupRowId { get; set; }

        public string MonthYear { get; set; }

        public string ProjectName { get; set; }

        public string Sep { get; set; }

    }

}