ddl无限绑定栏目（递归实现）_dede 栏目无限递归-优快云博客

本文介绍了一种使用C#语言从数据库中递归查询新闻种类及其子类别的方法。通过构建SQL连接并执行查询语句，实现了父类别下所有子类别的获取，并通过递归函数进一步获取每个子类别的子类别，直至没有更多的子类别为止。

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数据库中的表NewsKind

NewsKindID int
NewsKindName varchar
ParentID int

SqlConnection conn = new SqlConnection (System.Configuration.ConfigurationSettings.AppSettings["ConnectionString"]);
    conn.Open();
    string sqlstr = "select NewsKindID, NewsKindName,ParentID from NewsKind where ParentID=0 order by NewsKindID asc";
    SqlCommand cmd = new SqlCommand(sqlstr,conn);
    SqlDataReader dr = cmd.ExecuteReader();
    while(dr.Read())
    {
     ddlParentNewsKind.Items.Add(new ListItem(("┣")+dr["NewsKindName"].ToString(),dr["NewsKindID"].ToString()));
     if(dr["NewsKindID"].ToString()!=dr["ParentID"].ToString())
     {
      smallClass(long.Parse(dr["NewsKindID"].ToString()),"┃");
     }
    }

private void smallClass(long classId,string tempStr)
  {
   SqlConnection conn = new SqlConnection (System.Configuration.ConfigurationSettings.AppSettings["ConnectionString"]);
   conn.Open();
   string sqlstr = "select NewsKindID, NewsKindName,ParentID from NewsKind where ParentID="+classId+" order by NewsKindID asc";
   SqlCommand cmd = new SqlCommand(sqlstr,conn);
   SqlDataReader dr = cmd.ExecuteReader();
   while(dr.Read())
   {
    ddlParentNewsKind.Items.Add(new ListItem((tempStr+"┣")+dr["NewsKindName"].ToString(),dr["NewsKindID"].ToString()));
    if(dr["NewsKindID"].ToString()!=dr["ParentID"].ToString())
    {
     tempStr =tempStr +"┃";
     smallClass(long.Parse(dr["NewsKindID"].ToString()),tempStr);
    }
   }
  }