前言：
关于多级别菜单栏或者权限系统中部门上下级的树形遍历，oracle中有connect by来实现，mysql没有这样的便捷途径，所以MySQL遍历数据表是我们经常会遇到的头痛问题，下面通过存储过程来实现。
1，建立测试表和数据：
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，利用临时表和递归过程实现树的遍历（mysql的UDF不能递归调用）：
2.1，从某节点向下遍历子节点，递归生成临时表数据
-- 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$$
2.2，从某节点向上追溯根节点，递归生成临时表数据
-- pro_cre_parentlist
DELIMITER $$
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，实现类似Oracle SYS_CONNECT_BY_PATH的功能，递归过程输出某节点id路径
-- 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，递归过程输出某节点name路径
-- 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（m.sbmmt.com）！
