asp.net DropDownList 三级联动下拉菜单实现代码

复制代码 代码如下:
if (!IsPostBack)
{
//一级分类列表
this.DropDownList1.DataSource = dsbb.SelectSubjct1();
this.DropDownList1.DataTextField = "cName";
this.DropDownList1.DataValueField = "Ccode";
this.DropDownList1.DataBind();
this.DropDownList1.Items.Insert(0,new ListItem("请选择一级分类","0"));
this.DropDownList8.Items.Insert(0, new ListItem("请选择二级分类", "0"));
this.DropDownList9.Items.Insert(0,new ListItem ("请选择三级分类","0"));
//二级分类列表

}
/// <summary>
/// 绑定二级分类
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
protected void DropDownList1_SelectedIndexChanged(object sender, EventArgs e)
{
libs.Database.Dbbase dbb = new libs.Database.Dbbase();
if (Convert.ToInt32(this.DropDownList1.SelectedValue) == 0) //清除列表内容
{
this.DropDownList8.Items.Clear();
this.DropDownList8.Items.Insert(0, new ListItem("请选择二级分类", "0"));
this.DropDownList9.Items.Clear();
this.DropDownList9.Items.Insert(0, new ListItem("请选择三级分类", "0"));
}
else //二级分类列表
{
this.DropDownList8.DataSource = dbb.Selectsubjct2(this.DropDownList1.SelectedValue.Substring(0,2));
this.DropDownList8.DataTextField = "cName";
this.DropDownList8.DataValueField = "Ccode";
this.DropDownList8.DataBind();
this.DropDownList8.Items.Insert(0,new ListItem ("请选择二级分类","0"));
this.DropDownList9.Items.Clear();//清除第三分类
this.DropDownList9.Items.Insert(0, new ListItem("请选择三级分类", "0"));
}
}
/// <summary>
/// 绑定三级分类
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
protected void DropDownList8_SelectedIndexChanged(object sender, EventArgs e)
{
libs.Database.Dbbase dbase = new libs.Database.Dbbase();
this.DropDownList9.DataSource = dbase.selectsubject3(this.DropDownList8.SelectedValue.Substring(0,4));
this.DropDownList9.DataTextField = "cName";
this.DropDownList9.DataValueField = "Ccode";
this.DropDownList9.DataBind();
this.DropDownList9.Items.Insert(0,new ListItem("请选择三级分类","0"));
}


Dbbase.cs页：
复制代码 代码如下:
/// <summary>
/// 查询一级栏目
/// </summary>
/// <returns></returns>
public DataSet SelectSubjct1()
{
string con = System.Configuration.ConfigurationSettings.AppSettings["sqlconn"];
SqlConnection conn = new SqlConnection(con);
string sqlstr = "SELECT kndid, Ccode, cName, cLevel FROM kind WHERE cLevel = 1";
DataSet dst = new DataSet();
SqlDataAdapter sda = new SqlDataAdapter(sqlstr,conn);
try
{
sda.Fill(dst);
return dst;
}
catch (Exception ex)
{
throw new Exception(ex.Message);
}
finally
{
conn.Close();
}
}
/// <summary>
/// 查询二级栏目内容
/// </summary>
/// <param name="ccode"></param>
/// <returns></returns>
public DataSet Selectsubjct2(string ccode)
{
string conn1 = System.Configuration.ConfigurationSettings.AppSettings["sqlconn"];
SqlConnection conn = new SqlConnection(conn1);
string sqqq = "select kndid,Ccode,cName,cLevel from kind where cLevel = 2 and Ccode like '" + ccode + "%'";
DataSet dss = new DataSet();
SqlDataAdapter sdd = new SqlDataAdapter(sqqq,conn);
try
{
sdd.Fill(dss);
return dss;
}
catch (Exception ex)
{
throw new Exception(ex.Message);
}
finally
{
conn.Close();
}
}
/// <summary>
/// 查询三级栏目内容
/// </summary>
/// <param name="cde"></param>
/// <returns></returns>
public DataSet selectsubject3(string cde)
{
string conn2 = System.Configuration.ConfigurationSettings.AppSettings["sqlconn"];
SqlConnection conn = new SqlConnection(conn2);
string sqq = "select kndid,Ccode,cName,cLevel from kind where cLevel = 3 and Ccode like '" + cde + "%'";
DataSet dst = new DataSet();
SqlDataAdapter sdaa = new SqlDataAdapter(sqq,conn);
try
{
sdaa.Fill(dst);
return dst;
}
catch (Exception ex)
{
throw new Exception(ex.Message);
}
finally
{
conn.Close();
}
}

注意：DropDownList1_SelectedIndexChanged 事件，AutoPostBack="True"