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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:
? 1 2 3 4 5 6 7 8 9 10 11 12CREATE 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
? 1 2 3 4 5 6SELECT * 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
? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21SELECT 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
? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34SELECT 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)
? 1 2 3 4 5 6 7 8 9 10 11SELECT 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'
? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32-- 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 |
+---------+-----------+-----------+------+----------+-----------+