default.aspx.cs

asp.net + access 无刷新三级联动菜单使用简单 方便 容易学习

using System;
using System.Data;
using System.Configuration;
using System.Data.OleDb;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

public partial class _Default : System.Web.UI.Page
{   
    /// download from www.51aspx.com(５１ａｓｐｘ．ｃｏｍ)
    protected void Page_Load(object sender, EventArgs e)
    {
        AjaxPro.Utility.RegisterTypeForAjax(typeof(_Default)); //必要的
        if(!IsPostBack)BindDc();
    }

    /// <summary>
    /// 数据库连接
    /// </summary>
    /// <returns></returns>
    public OleDbConnection myConn()
    {
        string ConnStr = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + System.Web.HttpContext.Current.Server.MapPath(ConfigurationManager.AppSettings["dbpath"]);
        OleDbConnection conn = new OleDbConnection(ConnStr);
        try
        {
            conn.Open();
            return conn;
        }
        catch
        { 
            throw;
        }
    }
    
    /// <summary>
    /// 获取下级分类
    /// </summary>
    [AjaxPro.AjaxMethod]
    public DataSet getNextClass(string cid)
    {
        //因为不希望页面可以知道字段名称 所以 as txt,id as vol 如果是sql ser 可以用 = 
        //页面获取的 列名称 必须跟这个一同样 而且区分大小写 一般都是这个地方容易疏忽了
        //所以二级分类没变化
        string sql = @"select cname as txt,id as vol from webclass where parentid=" + cid;
        try
        {
            return getDs(sql);
        }
        catch
        {
            //throw;
            return null;
        }
    }
    

    /// <summary>
    /// 返回一个DataSet
    /// </summary>
    /// <param name="SQL"></param>
    /// <returns></returns>
    public DataSet getDs(string SQL)
    {
        OleDbConnection conn = myConn();
        DataSet Ds = new DataSet();
        OleDbDataAdapter Da = new OleDbDataAdapter(SQL, conn);
        try
        {   
            Da.Fill(Ds);
            return Ds;
        }
        catch
        {
            return null;
            //throw;
        }

    }
    /// <summary>
    /// //数据绑定
    /// </summary>
    private void BindDc()
    {
        //第一个
        string sql = @"select * from webclass where Parentid=0";
        ddl1.DataSource = getDs(sql);
        ddl1.DataTextField = "cname";
        ddl1.DataValueField = "id";
        ddl1.DataBind();
        if (ddl1.DataSource != null) ddl1.Attributes.Add("onchange", "showNext(this.options[selectedIndex].value,'ddl2');");

       
        //可以先判断 DropDownList.SelectedItem.Value
        //第二个
        sql = @"select * from webclass where parentid=" + ddl1.SelectedItem.Value;
        ddl2.DataSource = getDs(sql);
        ddl2.DataTextField = "cname";
        ddl2.DataValueField = "id";
        ddl2.DataBind();
        
        //第三个
        if (ddl2.DataSource != null) ddl2.Attributes.Add("onchange", "showNext(this.options[selectedIndex].value,'ddl3');");
        sql = @"select * from webclass where parentid=" + ddl2.SelectedItem.Value;
        ddl3.DataSource = getDs(sql);
        ddl3.DataTextField = "cname";
        ddl3.DataValueField = "id";
        ddl3.DataBind();
    
    }
}