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 |

+---------+-----------+-----------+------+----------+-----------+