当用户在下拉列表中单击不同的选项时，更改页面的内容

我得到了一个下拉列表。用户在选择不同的值时，我应该从下拉列表中得到用户所选择的选项的选项文本，然后从数据库中找到数据，并在网页上显示相关内容。如果用户再次更改选项，我应该根据选择的选项文本去检索不同的数据，并在网页上显示不同的内容。

我怎样才能做到这一点?谁有什么好主意让我开始?我在网上查了一下，但找不到有用的东西。

这是我的代码:

ASPX文件:

<asp:Dropdownlist ID="SelectionDropDownList" 
                  runat="server" Width="136px" 
                  EnableViewState="True" 
                  AppendDataBoundItems="true">
</asp:Dropdownlist>

CS文件:

//how the dropdown list is being populated out. Dropdown list is being populated out from what the user has selected from a listbox.
public void BindSomething()
{
    DateTime choosenDate = DateTime.MinValue;
    using (SqlConnection conn = new SqlConnection(dbConn))
    {
        using (SqlCommand cmd = new SqlCommand(spretrieve, conn))
        {
            //Lost to hold the values
            List<DateTime> listCopy = new List<DateTime>();
            DateTime dt;
            string values = String.Join(", ", ListBox1.Items.Cast<ListItem>().Where(i => i.Selected).Select(i => i.Text));
            if (values.Contains("Select All"))
            {
                //Loop through each items in listbox and then add it to list
                foreach (ListItem li in ListBox1.Items)
                {
                    if (DateTime.TryParse(li.Text, out dt))
                    {
                        listCopy.Add(dt);
                    }
                }
            }
            else
            {
                //Loop through each items in listbox and then add it to list
                foreach (ListItem li in ListBox1.Items)
                {
                    //check if item is selected
                    if (li.Selected == true)
                    {
                        //add items to list
                        listCopy.Add(DateTime.Parse(li.Text));
                    }
                }
            }
            //compare and sort so that the latest date comes on top
            listCopy.Sort((x, y) => y.CompareTo(x));
            //clear the items in dropdownlist
            SelectionDropDownList.Items.Clear();
            //set the datasource to dropdownlist
            SelectionDropDownList.DataSource = listCopy;
            //set the dateformatstring in dropdownlist
            SelectionDropDownList.DataTextFormatString = "{0:dd-MMM-yyyy}";
            //Bind the dropdownlist
            SelectionDropDownList.DataBind();
        }

如果有人能帮助我，我很感激，非常感谢!!

$(document).ready(function() {
$('#SelectionDropDownList').change(function(){
  //here you can add code for whatever you want to show   
});
});