二级链动

     protected void btnSend_Click(object sender, EventArgs e)
        {

            if (this.ddlSendName.SelectedValue == "-1")
            {
                Response.Write("<script language='javascript'>alert('发送方不能为空！');</script>");
                return;
            }
        }

        protected void ddlSendType_SelectedIndexChanged(object sender, EventArgs e)
        {
            if (this.ddlSendType.SelectedValue == "1")
            {
                ListItem li = new ListItem();
                li.Text = "无";
                li.Value = "-1";
                this.ddlSendName.Items.Clear();
                this.ddlSendName.Items.Add(li);
            }else
                if (this.ddlSendType.SelectedValue == "2")
                {
                    ListItem li = new ListItem();
                    li.Text = "yy";
                    li.Value = "1";
                    this.ddlSendName.Items.Clear();
                    this.ddlSendName.Items.Add(li);
                }
                else
                {
                    ListItem li = new ListItem();
                    li.Text = "yyyy";
                    li.Value = "2";
                    this.ddlSendName.Items.Clear();
                    this.ddlSendName.Items.Add(li);
                   
                }
        }