mysql 8.0 树形数据的查询

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参考文档

• https://dev.mysql.com/doc/refman/8.0/en/with.html

测试数据

-- ----------------------------
-- Table structure for tree
-- ----------------------------
DROP TABLE IF EXISTS `tree`;
CREATE TABLE `tree` (
  `id` int NOT NULL,
  `p_id` int DEFAULT NULL,
  `name` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of tree
-- ----------------------------
BEGIN;
INSERT INTO `tree` VALUES (1, NULL, 'A');
INSERT INTO `tree` VALUES (2, NULL, 'B');
INSERT INTO `tree` VALUES (3, 1, 'A3');
INSERT INTO `tree` VALUES (4, 1, 'A4');
INSERT INTO `tree` VALUES (5, 2, 'B5');
INSERT INTO `tree` VALUES (6, 2, 'B6');
INSERT INTO `tree` VALUES (7, 2, 'B7');
INSERT INTO `tree` VALUES (8, 3, 'A3-8');
INSERT INTO `tree` VALUES (9, 3, 'A3-9');
INSERT INTO `tree` VALUES (10, 3, 'A3-10');
INSERT INTO `tree` VALUES (11, 4, 'A4-11');
INSERT INTO `tree` VALUES (12, 4, 'A4-12');
INSERT INTO `tree` VALUES (13, 6, 'B6-13');
COMMIT;

SET FOREIGN_KEY_CHECKS = 1;

自顶向下查询子树

with RECURSIVE 
full_tree (id, p_id, name) AS
(select id, p_id, name from tree where p_id is null -- 查询条件
union all
select t.id, t.p_id, t.name from tree t
inner join full_tree on full_tree.id = t.p_id)
select * from full_tree;

查询结果：

+----+------+-------+
| id | p_id | name  |
+----+------+-------+
|  1 | NULL | A     |
|  2 | NULL | B     |
|  3 |    1 | A3    |
|  4 |    1 | A4    |
|  5 |    2 | B5    |
|  6 |    2 | B6    |
|  7 |    2 | B7    |
|  8 |    3 | A3-8  |
|  9 |    3 | A3-9  |
| 10 |    3 | A3-10 |
| 11 |    4 | A4-11 |
| 12 |    4 | A4-12 |
| 13 |    6 | B6-13 |
+----+------+-------+

自底向上查找所有节点

with RECURSIVE 
filter_tree (id, p_id, name) AS
(select id, p_id, name from tree where name like 'B%' -- 过滤条件
union all
select t.id, t.p_id, t.name from tree t
inner join filter_tree on filter_tree.p_id = t.id)
select distinct * from filter_tree;

查询结果:

+----+------+-------+
| id | p_id | name  |
+----+------+-------+
|  2 | NULL | B     |
|  5 |    2 | B5    |
|  6 |    2 | B6    |
|  7 |    2 | B7    |
| 13 |    6 | B6-13 |
+----+------+-------+