sql查询所有父级所有子级

Posted 2022-10-16 root_zhb

存在数据表如下，要求给定分类id，查询所有父级或子级

CREATE TABLE `smdm_item_category` (
  `category_id` double DEFAULT NULL,
  `category_code` varchar(255) DEFAULT NULL,
  `category_name` varchar(255) DEFAULT NULL,
  `parent_category_id` double DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb3;

INSERT INTO `smdm_item_category`(`category_id`, `category_code`, `category_name`, `parent_category_id`) VALUES (1752, 'IP', '间接采购\\r\\n', 0);
INSERT INTO `smdm_item_category`(`category_id`, `category_code`, `category_name`, `parent_category_id`) VALUES (1753, 'IP-ITEM\\r\\n', '间接材料\\r\\n', 1752);
INSERT INTO `smdm_item_category`(`category_id`, `category_code`, `category_name`, `parent_category_id`) VALUES (1773, 'IP-ITEM-CYS\\r\\n', '印刷品\\r\\n', 1753);
INSERT INTO `smdm_item_category`(`category_id`, `category_code`, `category_name`, `parent_category_id`) VALUES (1909, 'IP-ITEM-CYS-YHSC', '用户手册\\r\\n', 1773);
INSERT INTO `smdm_item_category`(`category_id`, `category_code`, `category_name`, `parent_category_id`) VALUES (2230, 'MANUAL,OWNERS', '用户手册\\r\\n', 1909);

查询所有子集
https://www.cnblogs.com/rainydayfmb/p/8028868.html

-- 查询1773的所有子集，ischild=0 包含自身，ischild=!0 不包含自身
SELECT
	category_id ,category_code,category_name
FROM
	(
	SELECT
		t1.category_id,
		t1.category_code,
		t1.category_name,
	IF
		( find_in_set( parent_category_id, @pids ) > 0, @pids := concat( @pids, ',', category_id ), 0 ) AS ischild 
	FROM
		( SELECT category_id, category_code,category_name,parent_category_id FROM smdm_item_category t ORDER BY parent_category_id, category_id ) t1,
		( SELECT @pids := 1773 ) t2 
	) t3 
WHERE
	ischild = 0

查所有父级

-- 递归查询所有父级，@r后面输入要查询的id
-- T1.lvl 表示层级  @l := 0 初始为0
SELECT T2.category_id, T2.category_code ,T2.category_name,T1.lvl
FROM ( 
    SELECT 
        @r AS _id, 
        (SELECT @r := parent_category_id FROM smdm_item_category WHERE category_id = _id) AS parent_category_id,
				@l := @l + 1 AS lvl
    FROM 
        (SELECT @r := 2230,@l := 0 ) vars, 
        smdm_item_category h 
    ) T1 
JOIN smdm_item_category T2 
ON T1._id = T2.category_id

---

---

#创建表

DROP TABLE IF EXISTS `test`;

CREATE TABLE `test` (
  `id` bigint NOT NULL AUTO_INCREMENT,
  `name` varchar(100) COLLATE utf8mb4_bin DEFAULT NULL,
  `parent_id` bigint DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=8 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin;

#插入数据

insert into `test` (`id`, `name`, `parent_id`) values('1','A','0');
insert into `test` (`id`, `name`, `parent_id`) values('2','B','1');
insert into `test` (`id`, `name`, `parent_id`) values('3','C','1');
insert into `test` (`id`, `name`, `parent_id`) values('4','D','2');
insert into `test` (`id`, `name`, `parent_id`) values('5','E','4');
insert into `test` (`id`, `name`, `parent_id`) values('6','F','1');
insert into `test` (`id`, `name`, `parent_id`) values('7','G','1');

#执行sql

SELECT T2.id, T2.name 
FROM ( 
    SELECT 
        @r AS _id, 
        (SELECT @r := parent_id FROM test WHERE id = _id) AS parent_id, 
        @l := @l + 1 AS lvl 
    FROM 
        (SELECT @r := 5, @l := 0) vars, 
        test h 
    ) T1 
JOIN test T2 
ON T1._id = T2.id 
ORDER BY T1.lvl DESC