N Tier development with Linq and WPF

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Reflection;

namespace UTILS.TestDB
{
    public class USR_USERInfo
    {
        public class TableStructure
        {
            public int USER_ID;
            public String USER_NAME;
            public String EMAIL;
            public DateTime ENTRY_DATE;
            public Boolean ACTIVE;

        }
        public class JoinedToUSR_USER_GROUP // Via USR_USER_TO_USER_GROUP
        {
            public int USER_ID;
            public String USER_NAME;
            public String EMAIL;
            public int USER_TO_USER_GROUP_ID;
            public int USER_GROUP_ID;
            public String USER_GROUP;
        }

    }
}