public List <TeacherModel> GetAllTeachers()
        {
            DataTable dt = new DataTable();

            using (OleDbCommand command = new OleDbCommand())
            {
                dt = GetMultipleQuery(TeacherStringsInner.GetAllTeachers());
            }

            List <TeacherModel> arrTeacher = new List <TeacherModel>();

            foreach (DataRow ms in dt.Rows)
            {
                arrTeacher.Add(TeacherModel.ToObject(ms));
            }
            return(arrTeacher);
        }