为下拉列表绑定数据并返回值

我是asp.net和c#的新手，我想得到一些下拉列表的帮助。我想在下拉列表中返回Students表中特定学生的ClassName值。我还希望用StudentClasses表中的所有classname填充下拉列表。但是我后面的代码确实在下拉列表中返回任何值。

谁能告诉我我做错了什么?

我有一个名为StudentClasses的表，包含以下数据，例如:

ClassID        ClassName
==
1              5B 
2              6C
3              K/1F

我有另一个名为Students的表，其中来自StudentClasses的ClassID是外键，例如:

StudentID      FirstName  LastName   ClassID
==
1              John       Smith      1
2              Sarah      Jones      2
3              Billy      Cain       2

我想在我的页面视图中返回以下内容:

Class将是StudentClasses中所有className的下拉列表，显示John Smith的Class, 5B。"名"answers"姓"是文本框。我也有一个更新按钮，所以我可以编辑细节要编辑Class，他们只能从下拉列表中选择。

First Name: John    Last Name: Smith      Class: 5B

这是aspx页面背后的代码。

protected void rptStudents_ItemDataBound(object sender, RepeaterItemEventArgs e)
{
    DropDownList ddlClassName = (DropDownList)e.Item.FindControl("ddlClassName");
    ddlClassName.DataTextField = "ClassName";
    ddlClassName.DataValueField = "ClassID";
    //this is the object that is bound to this particular item (row)
    StudentClass className = (StudentClass)e.Item.DataItem;
    //TO DO: student should contain class id instead of name.
    ddlClassName.SelectedValue = (className.ClassID).ToString();
    //to do get list of class items here and set datasource and then databind();
    Result<List<StudentClass>> result = StudentClassController.GetAllStudentClasses();
    ddlClassName.DataSource = result.Data;
    ddlClassName.DataBind();
}

protected void Page_Load(object sender, EventArgs e)
{
    PopulateDropDownList();
}

protected void Page_Load(object sender, EventArgs e)
{
   if (!IsPostBack)
   {
      PopulateDropDownList();
   }
}

    EmployeeList allemployees = EmployeeManager.GetList();
    EmployeeEDropDownList.Items.Clear();
    EmployeeEDropDownList.Items.Add("");  //add a blank item on top to simulate no selection
    foreach (Employee currentemp in allemployees)
    {
        EmployeeEDropDownList.Items.Add(new ListItem(currentemp.Name.FullNameE, currentemp.EmployeeID.ToString()));
    }