using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; using xUnitStudy.Model; namespace xUnitStudy.IBll { public interface IStudentBll { List Students { get; set; } List GetAll(); Student GetStudentById(int studentId); (bool result, Student student) AddStudent(Student student); (bool result, Student student) UpdateStudent(Student student); bool DeleteStudent(int userId); int GetTuition(int studentId); } }