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實現樹形的遍歷（關於多級菜單欄以及多級上下部門的查詢問題）

編輯：MySQL綜合教程

實現樹形的遍歷（關於多級菜單欄以及多級上下部門的查詢問題）

前言：關於多級別菜單欄或者權限系統中部門上下級的樹形遍歷，oracle中有connect by來實現，mysql沒有這樣的便捷途徑，所以MySQL遍歷數據表是我們經常會遇到的頭痛問題，下面通過存儲過程來實現。 1，建立測試表和數據：

DROP TABLE IF EXISTS csdn.channel;   
CREATE TABLE csdn.channel (   
  id INT(11) NOT NULL AUTO_INCREMENT,     
  cname VARCHAR(200) DEFAULT NULL,   
  parent_id INT(11) DEFAULT NULL,   
  PRIMARY KEY (id)   
) ENGINE=INNODB DEFAULT CHARSET=utf8;   
INSERT  INTO channel(id,cname,parent_id)    
VALUES (13,‘首頁‘,-1),   
       (14,‘TV580‘,-1),   
       (15,‘生活580‘,-1),   
       (16,‘左上幻燈片‘,13),   
       (17,‘幫忙‘,14),   
       (18,‘欄目簡介‘,17);  
DROP TABLE IF EXISTS channel;

2，利用臨時表和遞歸過程實現樹的遍歷（mysql的UDF不能遞歸調用）： 2.1，從某節點向下遍歷子節點，遞歸生成臨時表數據

-- pro_cre_childlist
DELIMITER $$     
DROP PROCEDURE IF EXISTS csdn.pro_cre_childlist$$   
CREATE PROCEDURE csdn.pro_cre_childlist(IN rootId INT,IN nDepth INT)   
BEGIN   
      DECLARE done INT DEFAULT 0;   
      DECLARE b INT;   
      DECLARE cur1 CURSOR FOR SELECT id FROM channel WHERE parent_id=rootId;   
      DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;   
      SET max_sp_recursion_depth=12;   
       
      INSERT INTO tmpLst VALUES (NULL,rootId,nDepth);   
       
      OPEN cur1;   
       
      FETCH cur1 INTO b;   
      WHILE done=0 DO   
              CALL pro_cre_childlist(b,nDepth+1);   
              FETCH cur1 INTO b;   
      END WHILE;   
       
      CLOSE cur1;   
END$$

2.2，從某節點向上追溯根節點，遞歸生成臨時表數據

-- pro_cre_parentlist
DELIMITER $$
DROP PROCEDURE IF EXISTS csdn.pro_cre_parentlist$$   
CREATE PROCEDURE csdn.pro_cre_parentlist(IN rootId INT,IN nDepth INT)   
BEGIN   
      DECLARE done INT DEFAULT 0;   
      DECLARE b INT;   
      DECLARE cur1 CURSOR FOR SELECT parent_id FROM channel WHERE id=rootId;   
      DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;   
      SET max_sp_recursion_depth=12;   
       
      INSERT INTO tmpLst VALUES (NULL,rootId,nDepth);   
       
      OPEN cur1;   
       
      FETCH cur1 INTO b;   
      WHILE done=0 DO   
              CALL pro_cre_parentlist(b,nDepth+1);   
              FETCH cur1 INTO b;   
      END WHILE;   
       
      CLOSE cur1;   
     END$$

2.3，實現類似Oracle SYS_CONNECT_BY_PATH的功能，遞歸過程輸出某節點id路徑

-- pro_cre_pathlist
DELIMITER $$
USE csdn$$
DROP PROCEDURE IF EXISTS pro_cre_pathlist$$
CREATE PROCEDURE pro_cre_pathlist(IN nid INT,IN delimit VARCHAR(10),INOUT pathstr VARCHAR(1000))
BEGIN                     
      DECLARE done INT DEFAULT 0;   
      DECLARE parentid INT DEFAULT 0;         
      DECLARE cur1 CURSOR FOR    
      SELECT t.parent_id,CONCAT(CAST(t.parent_id AS CHAR),delimit,pathstr)   
        FROM channel AS t WHERE t.id = nid;   
           
      DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;   
      SET max_sp_recursion_depth=12;                     
       
      OPEN cur1;   
       
      FETCH cur1 INTO parentid,pathstr;   
      WHILE done=0 DO              
              CALL pro_cre_pathlist(parentid,delimit,pathstr);   
              FETCH cur1 INTO parentid,pathstr;   
      END WHILE;   
            
      CLOSE cur1;    
END$$


DELIMITER ;

2.4，遞歸過程輸出某節點name路徑

-- pro_cre_pnlist
DELIMITER $$
USE csdn$$
DROP PROCEDURE IF EXISTS pro_cre_pnlist$$
CREATE PROCEDURE pro_cre_pnlist(IN nid INT,IN delimit VARCHAR(10),INOUT pathstr VARCHAR(1000))
BEGIN                     
      DECLARE done INT DEFAULT 0;   
      DECLARE parentid INT DEFAULT 0;         
      DECLARE cur1 CURSOR FOR    
      SELECT t.parent_id,CONCAT(t.cname,delimit,pathstr)   
        FROM channel AS t WHERE t.id = nid;   
           
      DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;   
      SET max_sp_recursion_depth=12;                     
       
      OPEN cur1;   
       
      FETCH cur1 INTO parentid,pathstr;   
      WHILE done=0 DO              
              CALL pro_cre_pnlist(parentid,delimit,pathstr);   
              FETCH cur1 INTO parentid,pathstr;   
      END WHILE;   
            
      CLOSE cur1;    
     END$$


DELIMITER ;

2.5，調用函數輸出id路徑

-- fn_tree_path
DELIMITER $$ 
DROP FUNCTION IF EXISTS csdn.fn_tree_path$$   
CREATE FUNCTION csdn.fn_tree_path(nid INT,delimit VARCHAR(10)) RETURNS VARCHAR(2000) CHARSET utf8   
BEGIN     
  DECLARE pathid VARCHAR(1000);   
     
  SET @pathid=CAST(nid AS CHAR);   
  CALL pro_cre_pathlist(nid,delimit,@pathid);   
     
  RETURN @pathid;   
END$$

2.6，調用函數輸出name路徑

-- fn_tree_pathname
-- 調用函數輸出name路徑   
DELIMITER $$ 
DROP FUNCTION IF EXISTS csdn.fn_tree_pathname$$   
CREATE FUNCTION csdn.fn_tree_pathname(nid INT,delimit VARCHAR(10)) RETURNS VARCHAR(2000) CHARSET utf8   
BEGIN     
  DECLARE pathid VARCHAR(1000);   
  SET @pathid=‘‘;       
  CALL pro_cre_pnlist(nid,delimit,@pathid);   
  RETURN @pathid;   
END$$  
DELIMITER ;

2.7，調用過程輸出子節點

-- pro_show_childLst  
DELIMITER $$
-- 調用過程輸出子節點   
DROP PROCEDURE IF EXISTS pro_show_childLst$$   
CREATE PROCEDURE pro_show_childLst(IN rootId INT)   
BEGIN   
      DROP TEMPORARY TABLE IF EXISTS tmpLst;   
      CREATE TEMPORARY TABLE IF NOT EXISTS tmpLst    
       (sno INT PRIMARY KEY AUTO_INCREMENT,id INT,depth INT);         
       
      CALL pro_cre_childlist(rootId,0);   
       
      SELECT channel.id,CONCAT(SPACE(tmpLst.depth*2),‘--‘,channel.cname) NAME,channel.parent_id,tmpLst.depth,fn_tree_path(channel.id,‘/‘) path,fn_tree_pathname(channel.id,‘/‘) pathname   
      FROM tmpLst,channel WHERE tmpLst.id=channel.id ORDER BY tmpLst.sno;   
     END$$

2.8，調用過程輸出父節點

-- pro_show_parentLst
DELIMITER $$
-- 調用過程輸出父節點   
DROP PROCEDURE IF EXISTS `pro_show_parentLst`$$   
CREATE PROCEDURE `pro_show_parentLst`(IN rootId INT)   
BEGIN   
      DROP TEMPORARY TABLE IF EXISTS tmpLst;   
      CREATE TEMPORARY TABLE IF NOT EXISTS tmpLst    
       (sno INT PRIMARY KEY AUTO_INCREMENT,id INT,depth INT);         
       
      CALL pro_cre_parentlist(rootId,0);   
      SELECT channel.id,CONCAT(SPACE(tmpLst.depth*2),‘--‘,channel.cname) NAME,channel.parent_id,tmpLst.depth,fn_tree_path(channel.id,‘/‘) path,fn_tree_pathname(channel.id,‘/‘) pathname   
      FROM tmpLst,channel WHERE tmpLst.id=channel.id ORDER BY tmpLst.sno;   
     END$$

3，開始測試： 3.1，從根節點開始顯示，顯示子節點集合：

mysql> CALL pro_show_childLst(-1); 
+----+-----------------------+-----------+-------+-------------+----------------------------+
| id | NAME                  | parent_id | depth | path        | pathname                   |
+----+-----------------------+-----------+-------+-------------+----------------------------+
| 13 |   --首頁              |        -1 |     1 | -1/13       | 首頁/                      |
| 16 |     --左上幻燈片      |        13 |     2 | -1/13/16    | 首頁/左上幻燈片/           |
| 14 |   --TV580             |        -1 |     1 | -1/14       | TV580/                     |
| 17 |     --幫忙            |        14 |     2 | -1/14/17    | TV580/幫忙/                |
| 18 |       --欄目簡介      |        17 |     3 | -1/14/17/18 | TV580/幫忙/欄目簡介/       |
| 15 |   --生活580           |        -1 |     1 | -1/15       | 生活580/                   |
+----+-----------------------+-----------+-------+-------------+----------------------------+
6 rows in set (0.05 sec)


Query OK, 0 rows affected (0.05 sec)

3.2，顯示首頁下面的子節點

CALL pro_show_childLst(13);  
mysql> CALL pro_show_childLst(13);   
+----+---------------------+-----------+-------+----------+-------------------------+
| id | NAME                | parent_id | depth | path     | pathname                |
+----+---------------------+-----------+-------+----------+-------------------------+
| 13 | --首頁              |        -1 |     0 | -1/13    | 首頁/                   |
| 16 |   --左上幻燈片      |        13 |     1 | -1/13/16 | 首頁/左上幻燈片/        |
+----+---------------------+-----------+-------+----------+-------------------------+
2 rows in set (0.02 sec)


Query OK, 0 rows affected (0.02 sec)


mysql>

3.3，顯示TV580下面的所有子節點

CALL pro_show_childLst(14);   
mysql> CALL pro_show_childLst(14);  
+----+--------------------+-----------+-------+-------------+----------------------------+
| id | NAME               | parent_id | depth | path        | pathname                   |
+----+--------------------+-----------+-------+-------------+----------------------------+
| 14 | --TV580            |        -1 |     0 | -1/14       | TV580/                     |
| 17 |   --幫忙           |        14 |     1 | -1/14/17    | TV580/幫忙/                |
| 18 |     --欄目簡介     |        17 |     2 | -1/14/17/18 | TV580/幫忙/欄目簡介/       |
+----+--------------------+-----------+-------+-------------+----------------------------+
3 rows in set (0.02 sec)


Query OK, 0 rows affected (0.02 sec)


mysql>

3.4，“幫忙”節點有一個子節點，顯示出來：

CALL pro_show_childLst(17);   
mysql> CALL pro_show_childLst(17); 
+----+------------------+-----------+-------+-------------+----------------------------+
| id | NAME             | parent_id | depth | path        | pathname                   |
+----+------------------+-----------+-------+-------------+----------------------------+
| 17 | --幫忙           |        14 |     0 | -1/14/17    | TV580/幫忙/                |
| 18 |   --欄目簡介     |        17 |     1 | -1/14/17/18 | TV580/幫忙/欄目簡介/       |
+----+------------------+-----------+-------+-------------+----------------------------+
2 rows in set (0.03 sec)


Query OK, 0 rows affected (0.03 sec)


mysql>

3.5，“欄目簡介”沒有子節點，所以只顯示最終節點：

mysql> CALL pro_show_childLst(18);   
+----+----------------+-----------+-------+-------------+----------------------------+
| id | NAME           | parent_id | depth | path        | pathname                   |
+----+----------------+-----------+-------+-------------+----------------------------+
| 18 | --欄目簡介     |        17 |     0 | -1/14/17/18 | TV580/幫忙/欄目簡介/       |
+----+----------------+-----------+-------+-------------+----------------------------+
1 row in set (0.36 sec)


Query OK, 0 rows affected (0.36 sec)


mysql>

3.6，顯示根節點的父節點

CALL pro_show_parentLst(-1);   
mysql> CALL pro_show_parentLst(-1);
Empty set (0.01 sec)


Query OK, 0 rows affected (0.01 sec)


mysql>

3.7，顯示“首頁”的父節點

CALL pro_show_parentLst(13);   
mysql> CALL pro_show_parentLst(13);   
+----+----------+-----------+-------+-------+----------+
| id | NAME     | parent_id | depth | path  | pathname |
+----+----------+-----------+-------+-------+----------+
| 13 | --首頁   |        -1 |     0 | -1/13 | 首頁/    |
+----+----------+-----------+-------+-------+----------+
1 row in set (0.02 sec)


Query OK, 0 rows affected (0.02 sec)


mysql>

3.8，顯示“TV580”的父節點，parent_id為-1

CALL pro_show_parentLst(14);   
mysql> CALL pro_show_parentLst(14);   
+----+---------+-----------+-------+-------+----------+
| id | NAME    | parent_id | depth | path  | pathname |
+----+---------+-----------+-------+-------+----------+
| 14 | --TV580 |        -1 |     0 | -1/14 | TV580/   |
+----+---------+-----------+-------+-------+----------+
1 row in set (0.02 sec)


Query OK, 0 rows affected (0.02 sec)

3.9，顯示“幫忙”節點的父節點

mysql>
CALL pro_show_parentLst(17);   
mysql> CALL pro_show_parentLst(17);   
+----+-----------+-----------+-------+----------+---------------+
| id | NAME      | parent_id | depth | path     | pathname      |
+----+-----------+-----------+-------+----------+---------------+
| 17 | --幫忙    |        14 |     0 | -1/14/17 | TV580/幫忙/   |
| 14 |   --TV580 |        -1 |     1 | -1/14    | TV580/        |
+----+-----------+-----------+-------+----------+---------------+
2 rows in set (0.02 sec)


Query OK, 0 rows affected (0.02 sec)


mysql>

3.10，顯示最低層節點“欄目簡介”的父節點

CALL pro_show_parentLst(18);  
mysql> CALL pro_show_parentLst(18);  
+----+----------------+-----------+-------+-------------+----------------------------+
| id | NAME           | parent_id | depth | path        | pathname                   |
+----+----------------+-----------+-------+-------------+----------------------------+
| 18 | --欄目簡介     |        17 |     0 | -1/14/17/18 | TV580/幫忙/欄目簡介/       |
| 17 |   --幫忙       |        14 |     1 | -1/14/17    | TV580/幫忙/                |
| 14 |     --TV580    |        -1 |     2 | -1/14       | TV580/                     |
+----+----------------+-----------+-------+-------------+----------------------------+
3 rows in set (0.02 sec)


Query OK, 0 rows affected (0.02 sec)
mysql>