求一个简单的递归算法

Question

ProductCategoryID ParentCategoryID Level  CategoryName  
----------------- ---------------- ----------- 
000               NULL             1           Temp
001               NULL             1           Mac
001001            001              2           Macbook
001001002         001001           3           Cases & bags  
001001003         001001           3           Screen Protectors 
001001004         001001           3           Cables & Adapters 
001001005         001001           3           Batteries & Chargers
001001006         001001           3           Parts & Repair
  这是表里面的数据
我要把这按分类绑定在dropdownlist
结果应该是
 -|Temp
 -|Mac
 -|Macbook
  --|Cases & bags
  --|Screen Protectors 
  --|Cables & Adapters 
  --|Parts & Repair求大家指点

Answer 1

递归？
--------------------------------
Function A()
{
     if(......)
      {
             A();
      }
}

Answer 2

Level个'-'+"|"+CategoryName
不就解决了？

Answer 3

实现我当然是实现了不过用的笨方法，通过级别加parent来分别找出来没用递归，但是想用递归的方法实现比较简单不会写

Answer 4

private void GetArticleCategory(string pid)
  {
   string strSpGroup = "Bjmti_KD_Ken_SEL_Group";
   SqlParameter[] spParamGroup = new SqlParameter[1];   
   spParamGroup[0] =new SqlParameter("@KD_ParentID",SqlDbType.VarChar,36); 
   spParamGroup[0].Value=pid;
            DataSet ds= DbHelperSQL.BjmtiDataSet(strSpGroup,spParamGroup);
     foreach(DataRow row in ds.Tables[0].Rows) 
     { 
    this.ddlKl.Items.Add(new ListItem(toadd + " " + row["KD_Name"].ToString(),row["KD_ID"].ToString()));
    toadd += "─┴";
    this.GetArticleCategory(row["KD_ID"].ToString());
    toadd = toadd.Substring(0, toadd.Length - 2);  //处理层次关系显示
   }
  }

Answer 5

http://blog.163.com/yuechunzhang00@126/blog/static/21245310201011721627485/

Answer 6

直接用SQL的递归查询 不用多次访问数据库.
with cte as 
(
select * From Product where Level = 1
Union all
select p.* From Product p join cte on p.ParentCategoryID = cte.ProductCategoryID  
)
slect ProductCategoryID,REPLICATE('-',level) + '|' + CategoryName from cte
order by ProductCategoryID 

Answer 7

 static void Main(string[] args)
        { 
DataTable dt = BindDataTable();
            Console.WriteLine("ProductCategoryID     ParentCategoryID       Level       CategoryName ");
            foreach (DataRow dr in dt.Rows)
            {
                
                Console.WriteLine(dr["ProductCategoryID"] + "          " + dr["ParentCategoryID"] + "                " + dr["Level"] + "                " + dr["CategoryName"]);
            }
            SetCateGoryName(dt, null, "ProductCategoryID", "ParentCategoryID", 1, '|', '-', "CategoryName");
            Console.WriteLine("--------------------------------------------");
            Console.WriteLine("CategoryName ");            foreach (DataRow dr in dt.Rows)
            {                Console.WriteLine(dr["CategoryName"]);
            }        }
static void SetCateGoryName(DataTable dt, string parentId,string idField,string parentIdField , int level, char fixedText, char trendsText, string textField)
        {
            foreach (DataRow row in dt.Rows)
            {
                if (int.Parse(row["Level"].ToString()) == level)
                {
                    if (string.IsNullOrEmpty(parentId))
                    {
                        GenerateText(row, fixedText, trendsText, textField);
                        string newParentId = row[idField].ToString();
                        SetCateGoryName(dt, newParentId, idField, parentIdField, level + 1, fixedText, trendsText, textField);
                    }
                    else
                    {
                        if (row[parentIdField].ToString().Trim() == parentId)
                        {
                            GenerateText(row, fixedText, trendsText, textField);
                            string newParentId = row[idField].ToString();
                            SetCateGoryName(dt, newParentId, idField, parentIdField, level + 1, fixedText, trendsText, textField);
                        }
                    }
                }
            }
        }        /// 生成处理符
        public static void GenerateText(DataRow dr,char fixedText, char trendsText,string textField)
        {
            int countTrends = int.Parse(dr["Level"].ToString());
            string text = string.Empty;
            text = text.PadLeft(countTrends, trendsText);
            text = text.PadRight(countTrends+1, fixedText);
            dr[textField] = text + dr[textField].ToString();
        }        private static List<object> GetColumnsListByColumnName(DataTable dt, string parentId, string idField, string parentIdField, int level)
        {
            if (!dt.Columns.Contains(parentIdField)) return null;
            if (!dt.Columns.Contains(idField)) return null;            List<object> columnsList = new List<object>();
            foreach (DataRow row in dt.Rows)
            {
                if (int.Parse(row["Level"].ToString()) == level)
                {
                    if (row[parentIdField].ToString() == parentId)
                    {
                        columnsList.Add(row[""]);
                    }
                }
            }
            return columnsList;
        }        static DataTable BindDataTable()
        {
            DataTable dt = new DataTable();            dt.Columns.Add("ProductCategoryID");
            dt.Columns.Add("ParentCategoryID");
            dt.Columns.Add("Level");
            dt.Columns.Add("CategoryName");            DataRow dr1 = dt.NewRow();
            object[] objs1 = {"000","            NULL","1","Temp"};
            dr1.ItemArray = objs1;
            dt.Rows.Add(dr1);            DataRow dr2 = dt.NewRow();
            object[] objs2 = { "001", "          NULL", "1", "Mac" };
            dr2.ItemArray = objs2;
            dt.Rows.Add(dr2);            DataRow dr3 = dt.NewRow();
            object[] objs3 = { "001001", "001", "2", "Macbook" };
            dr3.ItemArray = objs3;
            dt.Rows.Add(dr3);            DataRow dr4 = dt.NewRow();
            object[] objs4 = { "001001002", "001001", "3", "Cases & bags" };
            dr4.ItemArray = objs4;
            dt.Rows.Add(dr4);            DataRow dr5 = dt.NewRow();
            object[] objs5 = { "001001003", "001001", "3", "Screen Protectors" };
            dr5.ItemArray = objs5;
            dt.Rows.Add(dr5);            DataRow dr6 = dt.NewRow();
            object[] objs6 = { "001001004", "001001", "3", "Cables & Adapters" };
            dr6.ItemArray = objs6;
            dt.Rows.Add(dr6);            DataRow dr7 = dt.NewRow();
            object[] objs7 = { "001001005", "001001", "3", "Batteries & Chargers" };
            dr7.ItemArray = objs7;
            dt.Rows.Add(dr7);            DataRow dr8 = dt.NewRow();
            object[] objs8 = { "001001006", "001001", "3", "Parts & Repair" };
            dr8.ItemArray = objs8;
            dt.Rows.Add(dr8);
            return dt;
        }
临时写的

Answer 8

输出结果为:
ProductCategoryID     ParentCategoryID       Level       CategoryName
000                      NULL                1                Temp
001                    NULL                1                Mac
001001          001                2                Macbook
001001002          001001                3                Cases & bags
001001003          001001                3                Screen Protectors
001001004          001001                3                Cables & Adapters
001001005          001001                3                Batteries & Chargers
001001006          001001                3                Parts & Repair
--------------------------------------------
CategoryName
-|Temp
-|Mac
--|Macbook
---|Cases & bags
---|Screen Protectors
---|Cables & Adapters
---|Batteries & Chargers
---|Parts & Repair