C# BLL中的填充下拉框

如何填写数据库中的下拉列表？我有UI和BLL层和sp，但无法填充它。下拉名称为DRPDWnComplinantTypes。这类事情我做过很多次，但这次没有。请帮忙

protected void btnSave_Click(object sender, EventArgs e)
    {
        try
        {
            ComplainantBizz comBizz = new ComplainantBizz(txtName.Text, txtCNIC.Text, txtAddress.Text, txtContact.Text, Convert.ToInt32(DropdwnCompType.SelectedValue));
            ManageComplainant mngComplainantType = new ManageComplainant();

            bool Result = mngComplainantType.Insert(comBizz);


            if (Result == true)
            {
                HiddenFieldSetMessage.Value = "Saved";
                HiddenFieldShowMessage.Value = "True";
                Clear(txtName);
            }
            else
            {
                HiddenFieldSetMessage.Value = "RecordAlreadyExists";
                HiddenFieldShowMessage.Value = "True";
            }
        }
        catch (Exception)
        {
            HiddenFieldSetMessage.Value = "NotSaved";
            HiddenFieldShowMessage.Value = "True";
        }
    }

BLL：

SP: 这是我正在呼叫的SP

 alter  PROCEDURE SelectAllComplainantTypes_SP


AS
BEGIN

    Begin Try
      Select * from ComplainantTypes 
    End Try
    Begin Catch
     Select ERROR_MESSAGE() as ErrorMsg
    End Catch

END
GO

---

您需要将datatable return从函数绑定到dropdownlist，如中所示

dropdonlist.datasource=FillDropDown();
dropdownlist.datatextfield="yourTextColum";//in example column name "City"
dropdownlist.dataValueFiedl="yourValueColumn";//in example cloum name "ID"
dropdownlist.databind();

就这些

注意：如果您将从函数返回null，则会引发异常，如果未返回任何数据，则dropdownlist中不会显示任何数据

dropdonlist.datasource=FillDropDown();
dropdownlist.datatextfield="yourTextColum";//in example column name "City"
dropdownlist.dataValueFiedl="yourValueColumn";//in example cloum name "ID"
dropdownlist.databind();