时间：2021-07-01 10:21:17 帮助过：126人阅读
1.1. 前言
前面我们大概介绍了一下树结构表的基本使用。在我们项目中有好几块有用到多层级的概念。下面我们哪大家都比较熟悉的区域表来做演示。
1.2. 表结构和数据
区域表基本结构,可能在你的项目中还有包含其他字段。这边我只展示我们关心的字段:
CREATE TABLE `area` ( `area_id` int(11) NOT NULL AUTO_INCREMENT COMMENT '地区ID', `name` varchar(40) NOT NULL DEFAULT 'unkonw' COMMENT '地区名称', `area_code` varchar(10) NOT NULL DEFAULT 'unkonw' COMMENT '地区编码', `pid` int(11) DEFAULT NULL COMMENT '父id', `left_num` mediumint(8) unsigned NOT NULL COMMENT '节点左值', `right_num` mediumint(8) unsigned NOT NULL COMMENT '节点右值', PRIMARY KEY (`area_id`), KEY `idx$area$pid` (`pid`), KEY `idx$area$left_num` (`left_num`), KEY `idx$area$right_num` (`right_num`) )
区域表数据: area
导入到test表
mysql -uroot -proot test < area.sql
1.1. 区域表的基本操作
查看 '广州' 的相关信息
SELECT * FROM area WHERE name LIKE '%广州%'; +---------+-----------+-----------+------+----------+-----------+ | area_id | name | area_code | pid | left_num | right_num | +---------+-----------+-----------+------+----------+-----------+ | 2148 | 广州市 | 440100 | 2147 | 2879 | 2904 | +---------+-----------+-----------+------+----------+-----------+
查看 '广州' 所有孩子
SELECT c.* FROM area AS p, area AS c WHERE c.left_num BETWEEN p.left_num AND p.right_num AND p.area_id = 2148; +---------+-----------+-----------+------+----------+-----------+ | area_id | name | area_code | pid | left_num | right_num | +---------+-----------+-----------+------+----------+-----------+ | 2148 | 广州市 | 440100 | 2147 | 2879 | 2904 | | 2161 | 从化市 | 440184 | 2148 | 2880 | 2881 | | 2160 | 增城市 | 440183 | 2148 | 2882 | 2883 | | 2159 | 花都区 | 440114 | 2148 | 2884 | 2885 | | 2158 | 番禺区 | 440113 | 2148 | 2886 | 2887 | | 2157 | 黄埔区 | 440112 | 2148 | 2888 | 2889 | | 2156 | 白云区 | 440111 | 2148 | 2890 | 2891 | | 2154 | 天河区 | 440106 | 2148 | 2892 | 2893 | | 2153 | 海珠区 | 440105 | 2148 | 2894 | 2895 | | 2152 | 越秀区 | 440104 | 2148 | 2896 | 2897 | | 2151 | 荔湾区 | 440103 | 2148 | 2898 | 2899 | | 2150 | 东山区 | 230406 | 2148 | 2900 | 2901 | | 2149 | 其它区 | 440189 | 2148 | 2902 | 2903 | +---------+-----------+-----------+------+----------+-----------+
查看 '广州' 所有孩子 和 深度 并显示层级关系
SELECT sub_child.area_id,
(COUNT(sub_parent.name) - 1) AS depth,
CONCAT(REPEAT(' ', (COUNT(sub_parent.name) - 1)), sub_child.name) AS name
FROM (
SELECT child.*
FROM area AS parent, area AS child
WHERE child.left_num BETWEEN parent.left_num AND parent.right_num
AND parent.area_id = 2148
) AS sub_child, (
SELECT child.*
FROM area AS parent, area AS child
WHERE child.left_num BETWEEN parent.left_num AND parent.right_num
AND parent.area_id = 2148
) AS sub_parent
WHERE sub_child.left_num BETWEEN sub_parent.left_num AND sub_parent.right_num
GROUP BY sub_child.area_id
ORDER BY sub_child.left_num;
+---------+-------------+-------+
| area_id | name | depth |
+---------+-------------+-------+
| 2148 | 广州市 | 0 |
| 2161 | 从化市 | 1 |
| 2160 | 增城市 | 1 |
| 2159 | 花都区 | 1 |
| 2158 | 番禺区 | 1 |
| 2157 | 黄埔区 | 1 |
| 2156 | 白云区 | 1 |
| 2154 | 天河区 | 1 |
| 2153 | 海珠区 | 1 |
| 2152 | 越秀区 | 1 |
| 2151 | 荔湾区 | 1 |
| 2150 | 东山区 | 1 |
| 2149 | 其它区 | 1 |
+---------+-------------+-------+
显示 '广州' 的直系祖先(包括自己)
SELECT p.* FROM area AS p, area AS c WHERE c.left_num BETWEEN p.left_num AND p.right_num AND c.area_id = 2148; +---------+-----------+-----------+------+----------+-----------+ | area_id | name | area_code | pid | left_num | right_num | +---------+-----------+-----------+------+----------+-----------+ | 2147 | 广东省 | 440000 | 0 | 2580 | 2905 | | 2148 | 广州市 | 440100 | 2147 | 2879 | 2904 | | 3611 | 中国 | 100000 | -1 | 1 | 7218 | +---------+-----------+-----------+------+----------+-----------+
向 '广州' 插入一个地区 '南沙区'
-- 更新左右值 UPDATE area SET left_num = left_num + 2 WHERE left_num > 2879; UPDATE area SET right_num = right_num + 2 WHERE right_num > 2879; -- 插入 '南沙区' 信息 INSERT INTO area SELECT NULL, '南沙区', '440115', 2148, left_num + 1, left_num + 2 FROM area WHERE area_id = 2148; -- 查看是否满足要求 SELECT c.* FROM area AS p, area AS c WHERE c.left_num BETWEEN p.left_num AND p.right_num AND p.area_id = 2148; +---------+-----------+-----------+------+----------+-----------+ | area_id | name | area_code | pid | left_num | right_num | +---------+-----------+-----------+------+----------+-----------+ | 2148 | 广州市 | 440100 | 2147 | 2879 | 2906 | | 3612 | 南沙区 | 440115 | 2148 | 2880 | 2881 | | 2161 | 从化市 | 440184 | 2148 | 2882 | 2883 | | 2160 | 增城市 | 440183 | 2148 | 2884 | 2885 | | 2159 | 花都区 | 440114 | 2148 | 2886 | 2887 | | 2158 | 番禺区 | 440113 | 2148 | 2888 | 2889 | | 2157 | 黄埔区 | 440112 | 2148 | 2890 | 2891 | | 2156 | 白云区 | 440111 | 2148 | 2892 | 2893 | | 2154 | 天河区 | 440106 | 2148 | 2894 | 2895 | | 2153 | 海珠区 | 440105 | 2148 | 2896 | 2897 | | 2152 | 越秀区 | 440104 | 2148 | 2898 | 2899 | | 2151 | 荔湾区 | 440103 | 2148 | 2900 | 2901 | | 2150 | 东山区 | 230406 | 2148 | 2902 | 2903 | | 2149 | 其它区 | 440189 | 2148 | 2904 | 2905 | +---------+-----------+-----------+------+----------+-----------+