无限级树算法(递归)

此算法所用数据库为整个河南省地区（省、市、县）

/*
 * 无限级树算法
 */
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Data.SqlClient;
namespace ConApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            //Test.Dt();
            TestTree("0", 0);
            Console.ReadKey(true);
        }
        /*
         * 无限级树算法
         */
        static DataTable dt = Test.Dt();
        static int No = dt.Rows.Count;
        public static void TestTree(string f_id, int level)
        {
            int newlevel = 0;
            foreach (DataRow item in dt.Rows)
            {
                if (item.ItemArray[3].ToString().Trim() == f_id)
                {
                    for (int m = 0; m < level; m++)
                    {
                        Console.Write("{0}","--");
                    }
                    newlevel = level + 1;
                    Console.WriteLine("{0}", item.ItemArray[2].ToString());
                    TestTree(item.ItemArray[1].ToString(), newlevel);
                }
            }
        }
    }
    /// <summary>
    /// 数据操作类
    /// </summary>
    static class Test
    {
        public static SqlConnection Con()
        {
            SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=Area;Integrated Security=True");
            con.Open();
            return con;
        }
        public static DataTable Dt()
        {
            string sqlStr = "select * from [dbo].[Area]";
            SqlCommand cmd = new SqlCommand(sqlStr, Con());
            DataTable dt = new DataTable();
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            da.Fill(dt);
            return dt;
        }
    }
}