学步园

利用DropDownList的DropDownList_BuName_SelectedIndexChanged事件。

注意红色部分，不写     AutoPostBack="True"
，事件不起作用的。

Asp页面上：

                           商户名称：
                            <asp:DropDownList ID="DropDownList_BuName" runat="server" Width='200px'

                                AutoPostBack="True"

                                onselectedindexchanged="DropDownList_BuName_SelectedIndexChanged">
                            </asp:DropDownList>
                            <asp:DropDownList ID="DropDownList_Pos" runat="server" DataValueField="PosNum"

                                DataTextField="PosNum">
                            </asp:DropDownList>

C#后台代码：

 #region 选择商户之后，加载POS编号列表
        protected void DropDownList_BuName_SelectedIndexChanged(object sender, EventArgs e)
        {
            string buName = DropDownList_BuName.SelectedItem.ToString();
            if (buName != "-全部-")
            {
                DropDownList_Pos.DataSource = null;
                //根据商户编号查询所有的POS编号
                string querySql = "select PosNum from Tbl_Pos where Bucode = '" + buName.Split('-')[0].ToString() + "'";
                DataSet posDs = DBFhkHelper.queryDB(querySql);
                DataTable table = posDs.Tables[0];

                DataTable table1 = new DataTable();
                table1.Columns.Add("PosNum");
                DataRow drNew = table1.NewRow();
                drNew["PosNum"] = "-不选择POS-";
                table1.Rows.Add(drNew);
                table1.Merge(table);

                DropDownList_Pos.DataSource = table1;
                DropDownList_Pos.DataBind();
            }
            else
            {
                DropDownList_Pos.DataSource = null;
                DropDownList_Pos.Items.Add("-不选择POS-");
                DropDownList_Pos.DataBind();
            }
        }
        #endregion 选择商户之后，加载POS编号列表