MySQL多层级结构-区域表使用树详解

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 cWHERE 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 nameFROM （ SELECT child.*FROM area AS parent, area AS child WHERE child.left_num BETWEEN parent.left_num AND parent.right_numAND 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_numAND parent.area_id = 2148） AS sub_parentWHERE sub_child.left_num BETWEEN sub_parent.left_num AND sub_parent.right_numGROUP BY sub_child.area_idORDER 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 cWHERE 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 areaSELECT NULL, "南沙区", "440115", 2148, left_num + 1, left_num + 2FROM area WHERE area_id = 2148; -- 查看是否满足要求SELECT c.* FROM area AS p, area AS cWHERE 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 |+---------+-----------+-----------+------+----------+-----------+