C# n消息：无法比较数组中的两个元素“ #1- User,Role, Client Id, TimeStamp, rowVersion 201,READ,101, 1/18/2019, 2 201,WRITE,101, 1/18/2019, 1

n消息：无法比较数组中的两个元素“

#1- User,Role, Client Id, TimeStamp, rowVersion
    201,READ,101, 1/18/2019, 2
    201,WRITE,101, 1/18/2019, 1
    201,ADMIN,102, 1/18/2019, 3
    202,READ,102, 1/19/2019, 12

201,READ,101, 1/18/2019, 2
201,ADMIN,102, 1/18/2019, 3

201,READ,101, 1/18/2019, 2
201,ADMIN,102, 1/18/2019, 3

select * from(
select UserId,ClientId,RowVersion,RoleCode,row_number() 
over(partition by ClientId order by RowVersion desc) as roworder
from dbo.UR where UserId=6
) temp
where roworder=1

class ClientRole
{
    public int ClientId { get; set; }
    public string Role { get; set; }
    public int RowVersion { get; set; }
}

var clientRoles = new List<ClientRole>
{
    new ClientRole { ClientId = 101, Role = "READ", RowVersion = 2 },
    new ClientRole { ClientId = 101, Role = "WRITE", RowVersion = 1 },
    new ClientRole { ClientId = 102, Role = "ADMIN", RowVersion = 2 },
    new ClientRole { ClientId = 102, Role = "OTHER", RowVersion = 12 }
};

var clientRolesDic = (
    from cr in clientRoles
    group cr by cr.ClientId into g
    select g.OrderByDescending(i => i.RowVersion).First()
    )
    .ToDictionary(k => k.ClientId);

var results = list.GroupBy(x => x.ClientId)
                  .Select(x => x.OrderBy(y => y.rowVersion).Last())
                  .ToDictionary(x => x.ClientId);

var clientRoles = new []
{
    new { ClientId = 101, Role = "READ", RowVersion = 2 },
    new { ClientId = 101, Role = "WRITE", RowVersion = 1 },
    new { ClientId = 102, Role = "ADMIN", RowVersion = 3 },
    new { ClientId = 102, Role = "READ", RowVersion = 2 },
};

var result =
    from cr in clientRoles
    orderby cr.ClientId, cr.RowVersion descending
    group cr by cr.ClientId into gs
    from g in gs.Take(1)
    select g;

    new { ClientId = 101, Role = "READ", RowVersion = 2 },
    new { ClientId = 102, Role = "ADMIN", RowVersion = 3 },

using System;
using System.Linq;
public class Simple {
  public static void Main() {
            var userRoles = (new[] 
            { 
            new { clientid=1 , rowVersion = 1 , role="READ" },
            new { clientid=1 , rowVersion = 2 , role="EDIT" },
            new { clientid=2 , rowVersion = 3 , role="ADMIN" },
            new { clientid=1 , rowVersion = 4 , role="VIEW" }
        });

var o = userRoles.OrderByDescending(x => x.rowVersion)
                .GroupBy(x => x.clientid)
                .SelectMany(g =>
                   g.Select((j, i) => new { j.rowVersion, j.role, rn = i + 1 })
                   );

    var z =  o.Select(x => new {x.rowVersion, x.role, x.rn}).Where(a => a.rn==1);

      var results = userRoles.GroupBy(x => x.clientid)
                  .Select(x => x.OrderByDescending(y => y.rowVersion).First());

          Console.WriteLine("Solution #1");

        foreach (var i in z)
        {
            Console.WriteLine("{0} {1} {2}", i.rowVersion, i.role, i.rn);
        }

      Console.WriteLine("Solution #2");

      foreach (var k in results)
        {
            Console.WriteLine("{0} {1}", k.rowVersion, k.role);
        }

  }
  }