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@@ -0,0 +1,72 @@
+```asp
+using System.Web.UI.WebControls;
+
+namespace Demo1
+{
+ public partial class Province : System.Web.UI.Page
+ {
+ protected void Page_Load(object sender, EventArgs e)
+ {
+ if (!IsPostBack) {
+ //SelectCommand：设置数据源的select命令
+ SqlDataSource1.SelectCommand = "select id,cityName from city where type=1";
+```
+
+
+
+```asp
+ //初始化城市信息，父级id为2（北京市下的城市信息）
+ SqlDataSource2.SelectCommand = "select * from city where type=2 and pid=" + 2;
+
+ //初始化区县信息
+ SqlDataSource3.SelectCommand = "select * from city where type=3 and pid=(select top 1 id from city where pid=2)" ;
+ }
+ }
+
+ ///
+ /// 省份下拉框文本发生改变时执行的子程序
+ ///
+ ///
+ ///
+ protected void ddl_Province_TextChanged(object sender, EventArgs e)
+ {
+ //ddl_Province.SelectedValue获取省份下拉框的选中值，也就是选择的省份的id
+ SqlDataSource2.SelectCommand = "select * from city where type=2 and pid="+ddl_Province.SelectedValue;
+ }
+
+ protected void ddl_City_TextChanged(object sender, EventArgs e)
+ {
+ SqlDataSource3.SelectCommand = "select * from city where type=3 and pid="+ddl_City.SelectedValue;
+ }
+
+ protected void SqlDataSource1_Selecting(object sender, SqlDataSourceSelectingEventArgs e)
+ {
+
+ }
+
+ protected void SqlDataSource3_Selecting(object sender, SqlDataSourceSelectingEventArgs e)
+ {
+
+ }
+}
+```
+
+
+
+
+
+
+
+
+
+ 省份：
+
+
+
+
+
+ 城市：
+
+ 区县：
+
+