semesterWork/data/DAO/Group.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Data.DAO
{
    public class Group
    {
        public int GroupId { get; set; }
        public string GroupName { get; set; }

        public virtual IEnumerable<Student> Students { get; set; }
        public virtual ICollection<Subject> Subjects { get; set; }
        public virtual ICollection<GroupSubject> GroupSubjects { get; set; }
    }
}