递归调用（id,pid,name)根据一个id获取它所有的子节点

用c#做的

        public List<int> list = new List<int>();//把所有的id都装入list中
        SqlConnection con=null;
        private void button1_Click(object sender, EventArgs e)//测试方法
        {
            GetIdsByName("软件");
        }

     //根据name获取ID
       public void GetIdsByName(String name）
        {
          con = new SqlConnection(@"Data Source=.\sqlexpress;Initial Catalog=BBS;Integrated Security=True");
            String sql = "select boardID from Board where boardName='"+name+"'";//根据A查询得到ID
            con.Open();
            SqlCommand cmd = new SqlCommand(sql ,con);
           int id=Convert.ToInt32(cmd.ExecuteScalar());
           getIDs(id);//去查它的子ids
           con.Close();
        }       

        public void getIDs(int id)//根据一个id查找它下面所有的子ID
        {
            String childsql = "select boardID from Board where parentId=" + id;// 根据父id查出它的所有子ID
            SqlCommand ccmd = new SqlCommand(childsql, con);
            SqlDataReader reader = ccmd.ExecuteReader();
             List<int> ids = new List<int>();
            while(reader.Read())
            {
                ids.Add(Convert.ToInt32(reader[0]));//把ids放入集合java中不用，C#中为了下面遍历用
                list.Add(Convert.ToInt32(reader[0]));//添加到指定集合中
               // getIDs(Convert.ToInt32(reader[0]));//在java里可以直接调用
               
            }
            reader.Close();
            //在java里就不用了
            foreach (int cid in ids)
            {
                getIDs(cid);//递归调用
            }
        }