MySQL implementiert Tree Traversal (Fragen zu mehrstufigen Menüleisten und mehrstufigen oberen und unteren Abteilungen)

Vorwort:
Über Baumdurchquerung der oberen und unteren Abteilungsebenen in mehrstufigen Menüleisten oder Berechtigungen Systeme, Oracle Es gibt keine so bequeme Möglichkeit, MySQL zu erreichen, daher ist das Durchlaufen der Datentabelle ein Problem, auf das wir häufig stoßen. Das Folgende wird durch gespeicherte Prozeduren implementiert.


1. Testtabellen und Daten erstellen:

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,'首页',-1),   
       (14,'TV580',-1),   
       (15,'生活580',-1),   
       (16,'左上幻灯片',13),   
       (17,'帮忙',14),   
       (18,'栏目简介',17);  
DROP TABLE IF EXISTS channel;

2, unter Verwendung temporärer Tabellen Und der rekursive Prozess implementiert die Baumdurchquerung (die UDF von MySQL kann nicht rekursiv aufgerufen werden):

2.1, von einem Knoten nach unten durchqueren die untergeordneten Knoten und generieren rekursiv temporäre Tabellendaten

-- 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, verfolgen Sie von einem bestimmten Knoten nach oben zum Wurzelknoten und generieren Sie rekursiv temporäre Tabellendaten

-- 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, implementiert eine Funktion ähnlich wie Oracle SYS_CONNECT_BY_PATH, der rekursive Prozess gibt einen Knoten-ID-Pfad aus
< 2.4, Rekursion Der Prozess gibt einen Knotennamenpfad aus

-- 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 ;

-- 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，调用函数输出id路径

-- 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，调用函数输出name路径

-- fn_tree_pathname
-- 调用函数输出name路径   
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，调用过程输出子节点

-- pro_show_childLst  
DELIMITER $$
-- 调用过程输出子节点   
DROP PROCEDURE IF EXISTS pro_show_childLst$$   
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，调用过程输出父节点

-- pro_show_parentLst
DELIMITER $$
-- 调用过程输出父节点   
DROP PROCEDURE IF EXISTS `pro_show_parentLst`$$   
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，开始测试：
3.1，从根节点开始显示，显示子节点集合：

mysql> CALL pro_show_childLst(-1); 
+----+-----------------------+-----------+-------+-------------+----------------------------+
| id | NAME                  | parent_id | depth | path        | pathname                   |
+----+-----------------------+-----------+-------+-------------+----------------------------+
| 13 |   --首页              |        -1 |     1 | -1/13       | 首页/                      |
| 16 |     --左上幻灯片      |        13 |     2 | -1/13/16    | 首页/左上幻灯片/           |
| 14 |   --TV580             |        -1 |     1 | -1/14       | TV580/                     |
| 17 |     --帮忙            |        14 |     2 | -1/14/17    | TV580/帮忙/                |
| 18 |       --栏目简介      |        17 |     3 | -1/14/17/18 | TV580/帮忙/栏目简介/       |
| 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，显示首页下面的子节点

CALL pro_show_childLst(13);  
mysql> CALL pro_show_childLst(13);   
+----+---------------------+-----------+-------+----------+-------------------------+
| id | NAME                | parent_id | depth | path     | pathname                |
+----+---------------------+-----------+-------+----------+-------------------------+
| 13 | --首页              |        -1 |     0 | -1/13    | 首页/                   |
| 16 |   --左上幻灯片      |        13 |     1 | -1/13/16 | 首页/左上幻灯片/        |
+----+---------------------+-----------+-------+----------+-------------------------+
2 rows in set (0.02 sec)
Query OK, 0 rows affected (0.02 sec)
mysql>

3.3，显示TV580下面的所有子节点

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 |   --帮忙           |        14 |     1 | -1/14/17    | TV580/帮忙/                |
| 18 |     --栏目简介     |        17 |     2 | -1/14/17/18 | TV580/帮忙/栏目简介/       |
+----+--------------------+-----------+-------+-------------+----------------------------+
3 rows in set (0.02 sec)
Query OK, 0 rows affected (0.02 sec)
mysql>

3.4，“帮忙”节点有一个子节点，显示出来：

CALL pro_show_childLst(17);   
mysql> CALL pro_show_childLst(17); 
+----+------------------+-----------+-------+-------------+----------------------------+
| id | NAME             | parent_id | depth | path        | pathname                   |
+----+------------------+-----------+-------+-------------+----------------------------+
| 17 | --帮忙           |        14 |     0 | -1/14/17    | TV580/帮忙/                |
| 18 |   --栏目简介     |        17 |     1 | -1/14/17/18 | TV580/帮忙/栏目简介/       |
+----+------------------+-----------+-------+-------------+----------------------------+
2 rows in set (0.03 sec)
Query OK, 0 rows affected (0.03 sec)
mysql>

3.5，“栏目简介”没有子节点，所以只显示最终节点：

mysql> CALL pro_show_childLst(18);   
+----+----------------+-----------+-------+-------------+----------------------------+
| id | NAME           | parent_id | depth | path        | pathname                   |
+----+----------------+-----------+-------+-------------+----------------------------+
| 18 | --栏目简介     |        17 |     0 | -1/14/17/18 | TV580/帮忙/栏目简介/       |
+----+----------------+-----------+-------+-------------+----------------------------+
1 row in set (0.36 sec)
Query OK, 0 rows affected (0.36 sec)
mysql>

3.6，显示根节点的父节点

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，显示“首页”的父节点

CALL pro_show_parentLst(13);   
mysql> CALL pro_show_parentLst(13);   
+----+----------+-----------+-------+-------+----------+
| id | NAME     | parent_id | depth | path  | pathname |
+----+----------+-----------+-------+-------+----------+
| 13 | --首页   |        -1 |     0 | -1/13 | 首页/    |
+----+----------+-----------+-------+-------+----------+
1 row in set (0.02 sec)
Query OK, 0 rows affected (0.02 sec)
mysql>

3.8，显示“TV580”的父节点，parent_id为-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，显示“帮忙”节点的父节点

mysql>
CALL pro_show_parentLst(17);   
mysql> CALL pro_show_parentLst(17);   
+----+-----------+-----------+-------+----------+---------------+
| id | NAME      | parent_id | depth | path     | pathname      |
+----+-----------+-----------+-------+----------+---------------+
| 17 | --帮忙    |        14 |     0 | -1/14/17 | TV580/帮忙/   |
| 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，显示最低层节点“栏目简介”的父节点

CALL pro_show_parentLst(18);  
mysql> CALL pro_show_parentLst(18);  
+----+----------------+-----------+-------+-------------+----------------------------+
| id | NAME           | parent_id | depth | path        | pathname                   |
+----+----------------+-----------+-------+-------------+----------------------------+
| 18 | --栏目简介     |        17 |     0 | -1/14/17/18 | TV580/帮忙/栏目简介/       |
| 17 |   --帮忙       |        14 |     1 | -1/14/17    | TV580/帮忙/                |
| 14 |     --TV580    |        -1 |     2 | -1/14       | TV580/                     |
+----+----------------+-----------+-------+-------------+----------------------------+
3 rows in set (0.02 sec)
Query OK, 0 rows affected (0.02 sec)
mysql>

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