DropDownList无限级分类(灵活控制显示形式)

主要使用递归实现，数据库结构：

最终样式：

  
    

   
     
   
     protected
   
      
   
     void
   
      Page_Load(
   
     object
   
      sender, EventArgs e)
 {
 
   
     if
   
      (
   
     !
   
     Page.IsPostBack)
 {
 BindDrpClass();
 }
 }
 
   
     //
   
     绑定顶级分类
   
     

   
      
   
     private
   
      
   
     void
   
      BindDrpClass()
 {
 Bll.Class classSystem 
   
     =
   
      
   
     new
   
      Bll.Class();
 DataTable dt 
   
     =
   
      classSystem.GetClassList(
   
     ""
   
     ).Tables[
   
     0
   
     ];
 ddlClass.Items.Clear();
 ddlClass.Items.Add(
   
     new
   
      ListItem(
   
     "
   
     添加根栏目
   
     "
   
     ,
   
     "
   
     0
   
     "
   
     ));
 DataRow[] drs 
   
     =
   
      dt.Select(
   
     "
   
     ParentID= 
   
     "
   
      
   
     +
   
      
   
     0
   
     );

 
   
     foreach
   
      (DataRow dr 
   
     in
   
      drs)
 {
 
   
     string
   
      classid 
   
     =
   
      dr[
   
     "
   
     ClassID
   
     "
   
     ].ToString();
 
   
     string
   
      classname 
   
     =
   
      dr[
   
     "
   
     ClassName
   
     "
   
     ].ToString();
 
   
     //
   
     顶级分类显示形式
   
     

   
      classname 
   
     =
   
      
   
     "
   
     ╋
   
     "
   
      
   
     +
   
      classname;

 ddlClass.Items.Add(
   
     new
   
      ListItem(classname, classid));
 
   
     int
   
      sonparentid 
   
     =
   
      
   
     int
   
     .Parse(classid);
 
   
     string
   
      blank 
   
     =
   
      
   
     "
   
     ├
   
     "
   
     ;
 
   
     //
   
     递归子分类方法
   
     

   
      BindNode(sonparentid, dt, blank);
 }
 ddlClass.DataBind();
 }
 
   
     //
   
     绑定子分类
   
     

   
      
   
     private
   
      
   
     void
   
      BindNode(
   
     int
   
      parentid, DataTable dt, 
   
     string
   
      blank)
 {
 DataRow[] drs 
   
     =
   
      dt.Select(
   
     "
   
     ParentID= 
   
     "
   
      
   
     +
   
      parentid);

 
   
     foreach
   
      (DataRow dr 
   
     in
   
      drs)
 {
 
   
     string
   
      classid 
   
     =
   
      dr[
   
     "
   
     ClassID
   
     "
   
     ].ToString();
 
   
     string
   
      classname 
   
     =
   
      dr[
   
     "
   
     ClassName
   
     "
   
     ].ToString();

 classname 
   
     =
   
      blank 
   
     +
   
      classname;
 ddlClass.Items.Add(
   
     new
   
      ListItem(classname, classid));

 
   
     int
   
      sonparentid 
   
     =
   
      
   
     int
   
     .Parse(classid);
 
   
     string
   
      blank2 
   
     =
   
      blank 
   
     +
   
      
   
     "
   
     ─
   
     "
   
     ;

 BindNode(sonparentid, dt, blank2);
 }
 }
  
    

 

 

代码数据访问（Bll里面的classSystem方法

   
     

    
      
    
      public
    
       DataSet GetClassList(
    
      string
    
       strWhere)
 {
 StringBuilder strSql 
    
      =
    
       
    
      new
    
       StringBuilder();
 strSql.Append(
    
      "
    
      select * from tb_Class 
    
      "
    
      );
 
    
      if
    
       (strWhere.Trim() 
    
      !=
    
       
    
      ""
    
      )
 {
 strSql.Append(
    
      "
    
       where 
    
      "
    
       
    
      +
    
       strWhere);
 }
 
    
      return
    
       SqlHelper.ExecuteDataset(SqlHelper.ConnString, CommandType.Text, strSql.ToString());
 }
   
     

来源：http://www.cnblogs.com/chensubo/archive/2008/02/11/1067037.html