Dynamic data filling of ComboBox drop-down box control in winform

 

   private System.Windows.Forms.ComboBox cboClass;

  //始化班级下拉框
            this.cboClass.DataSource = objClassService.GetAllClass();
            this.cboClass.DisplayMember = "ClassName";//设置下拉框显示文本
            this.cboClass.ValueMember = "ClassId";//设置下拉框显示文本对应的value
            this.cboClass.SelectedIndex = -1;//默认不选中任何班级

 /// <summary>
        /// 查询班级对象
        /// </summary>
        /// <returns></returns>
        public  List<StudentClass> GetAllClass()
        {
            string sql = "select ClassName ,ClassId from StudentClass";
            SqlDataReader objReader = SQLHelper.GetReader(sql);
            List<StudentClass> list = new List<StudentClass>();
            while (objReader.Read())
            {
                list.Add(new StudentClass()