MySQL implements tree traversal (questions about multi-level menu bars and multi-level upper and lower departments)

Foreword:
About tree traversal of upper and lower levels of departments in multi-level menu bars or permission systems, oracle There is connect by in MySQL to achieve this. MySQL does not have such a convenient way, so MySQL traversing the data table is a headache we often encounter. The following is implemented through stored procedures.


1, create test table and data:

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, using temporary tables and recursion The process implements tree traversal (mysql's UDF cannot be called recursively):

2.1, traverse from a certain node downwards to the child Node, recursively generate temporary table data
##

-- 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, trace upward from a certain node to the root node, and recursively generate temporary table data

-- 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, implement a function similar to Oracle SYS_CONNECT_BY_PATH, the recursive process outputs a node id path

-- 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, the recursive process outputs a node name path

-- 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>

 以上就是MySQL 实现树形的遍历（关于多级菜单栏以及多级上下部门的查询问题） 的内容，更多相关内容请关注PHP中文网（www.php.cn）！