Recursive small case (Reprinted finishing)

1.sql statement to achieve

 // Get all children

WITH temps  
AS  
(  
SELECT * FROM [its].[dbo].[Citys]  WHERE areaid = 2  
UNION ALL  
SELECT m.* FROM [its].[dbo].[Citys]  AS m  
INNER JOIN temps AS child ON m.ParentId = child.areaid  
)  
SELECT * FROM temps

 

 // Get all of its parent

WITH TEMP AS
(
The SELECT * the FROM [ITS] [the dbo] [the Citys] = the WHERE ArealD.. ' 2 ' - primary key ID table
UNION ALL
SELECT T0.* FROM TEMP,[its].[dbo].[Citys] T0 WHERE TEMP.ParentId=T0.areaid --父级ID==子级ID
)
SELECT * FROM TEMP;

 

2.C # realization

using System;
using System.Collections.Generic;
using System.Linq;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {

            var data = GetData();

            // Get all subordinate 
            var Query = GetSons (Data, . 1 );

            // Get all higher
             @ var = GetFatherList Query (Data,. 5); 
            Console.WriteLine ( " Id \ t zoning \ t Parent ID \ t hierarchy \ t " );
            query.ToList().ForEach(q => Console.WriteLine("{0}\t {1}\t {2}\t {3}\t", q.Id, q.Name, q.Fid, q.Level));

            Console.ReadLine();
        }

        #region test data
         public  static the IList <MENU> the GetData ()
        {
            var list = new List<menu>();
            list.Add(new menu { Id = 1, Name = "广东省", Fid = 0, Level = 1 });
            list.Add(new menu { Id = 2, Name = "深圳市", Fid = 1, Level = 2 });
            list.Add(new menu { Id = 3, Name = "南山区", Fid = 2, Level = 3 });
            list.Add(new menu { Id = 4, Name = "福田区", Fid = 2, Level = 3 });
            list.Add(new menu { Id = 5, Name = "上梅林", Fid = 4, Level = 4 });
            list.Add(new menu { Id = 6, Name = "下梅林", Fid = 4, Level = 4 });
            list.Add(new menu { Id = 7, Name = "车公庙", Fid = 4, Level = 4 });
            list.Add(new menu { Id = 8, Name = "蛇口", Fid = 5, Level = 4 });
            list.Add(new menu { Id = 9, Name = "科技园", Fid = 5, Level = 4 });
            list.Add(new menu { Id = 10, Name = "湖南省", Fid = 0, Level = 1 });
            list.Add(new menu { Id = 11, Name = "长沙市", Fid = 10, Level = 2 });
            list.Add(new menu { Id = 12, Name = "芙蓉区", Fid = 11, Level = 3 });
            return list;
        }
        #endregion

        #region Get all subordinate
         public  static the IEnumerable <MENU> GetSons (the IList <MENU> List, int Fid)
        {
            var query = list.Where(p => p.Id == Fid).ToList();
            var list2 = query.Concat(GetSonList(list, Fid));
            return list2;
        }

        public static IEnumerable<menu> GetSonList(IList<menu> list, int Fid)
        {
            var query = list.Where(p => p.Fid == Fid).ToList();
            return query.ToList().Concat(query.ToList().SelectMany(t => GetSonList(list, t.Id)));
        }
        #endregion

        #region Get all higher
         public  static the IEnumerable <MENU> GetFatherList (the IList <MENU> List, int Id)
        {
            var query = list.Where(p => p.Id == Id).ToList();
            return query.ToList().Concat(query.ToList().SelectMany(t => GetFatherList(list, t.Fid)));
        }
        #endregion

        #region entity class
         public  class the MENU
        {
            public int Id { set; get; }
            public string Name { set; get; }
            public int Fid { set; get; }
            public int Level { set; get; }
        }
        #endregion
    }
}