mysql 8.0中 树形数据的查询

- [数据准备](https://cloud.tencent.com/developer)
- [自顶向下查询子树](https://cloud.tencent.com/developer)
- [自底向上查找所有节点](https://cloud.tencent.com/developer)
- [根据子节点id向上查找](https://cloud.tencent.com/developer)

WITH recursive 表名 AS ( 
	初始语句（非递归部分） 
	UNION ALL 
	递归部分语句
)
[ SELECT| INSERT | UPDATE | DELETE]

-- ----------------------------
-- 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;

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;

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;

with RECURSIVE 
filter_tree (id, p_id, name) AS
(select id, p_id, name from tree where  id=13 -- 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;