Getting Parent Child hierarchy

问题

I'm trying to get ancestors of a child (dog) upto Level 5. For Example in attached picture I'll be sending "Spencer di Casa Massarelli" and in result want to have associated parents (both father and mother). In my DB structure I've used father_id and mother_id.

DB & version: 10.4.11-MariaDB

Table Script:

CREATE TABLE `dogs` (
  `dog_id` int(11) NOT NULL,
  `name` varchar(255) DEFAULT NULL,
  `father_id` int(11) DEFAULT NULL,
  `moter_id` int(11) DEFAULT NULL,
  PRIMARY KEY (`dog_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

INSERT INTO `dogs` VALUES ('0', null, null, null);
INSERT INTO `dogs` VALUES ('1', 'Father', null, null);
INSERT INTO `dogs` VALUES ('2', 'Mother', null, null);
INSERT INTO `dogs` VALUES ('3', 'Father1', null, null);
INSERT INTO `dogs` VALUES ('4', 'Mother2', null, null);
INSERT INTO `dogs` VALUES ('5', 'Son', '1', '2');
INSERT INTO `dogs` VALUES ('6', 'Daughter', '3', '4');
INSERT INTO `dogs` VALUES ('7', 'GrandSon', '5', '6');

I've tried following self join query but the problem is I'm unable to get right parents i.e., parents(both father and mother) of first parent.

SELECT t1.name AS lev1, 
       t2.name AS lev2Father, 
       t3.name AS lev2Mother, 
       t4.name AS level3Father, 
       t5.name AS level3Mother, 
       t6.name AS level4Father, 
       t7.name AS level4Mother, 
       t8.name AS level5Father, 
       t9.name AS level5Mother, 
       t10.name AS level6Father, 
       t11.name AS level6Mother 
FROM dogs AS t1 
LEFT JOIN dogs AS t2 ON t2.dog_id = t1.father_id 
LEFT JOIN dogs AS t3 ON t3.dog_id = t1.mother_id 
LEFT JOIN dogs AS t4 ON t4.dog_id = t2.father_id 
LEFT JOIN dogs AS t5 ON t5.dog_id = t2.mother_id 
LEFT JOIN dogs AS t6 ON t6.dog_id = t4.father_id 
LEFT JOIN dogs AS t7 ON t7.dog_id = t4.mother_id 
LEFT JOIN dogs AS t8 ON t8.dog_id = t6.father_id 
LEFT JOIN dogs AS t9 ON t9.dog_id = t6.mother_id 
LEFT JOIN dogs AS t10 ON t10.dog_id = t8.father_id 
LEFT JOIN dogs AS t11 ON t11.dog_id = t8.mother_id 
WHERE t1.dog_id = 7

回答1:

WITH RECURSIVE
cte AS (
SELECT *, 0 level, '      ' relation
FROM dogs
WHERE dog_id = 7

UNION ALL

SELECT dogs.*, level + 1, 'father'
FROM dogs
JOIN cte ON cte.father_id = dogs.dog_id
WHERE level < 5

UNION ALL

SELECT dogs.*, level + 1, 'mother'
FROM dogs
JOIN cte ON cte.mother_id = dogs.dog_id
WHERE level < 5
)
SELECT *
FROM cte
ORDER BY level, relation;

fiddle

Result

dog_id | name     | father_id | mother_id | level | relation
-----: | :------- | --------: | --------: | ----: | :-------
     7 | GrandSon |         5 |         6 |     0 |         
     5 | Son      |         1 |         2 |     1 | father  
     6 | Daughter |         3 |         4 |     1 | mother  
     1 | Father   |      null |      null |     2 | father  
     3 | Father1  |      null |      null |     2 | father  
     2 | Mother   |      null |      null |     2 | mother  
     4 | Mother2  |      null |      null |     2 | mother

来源：https://stackoverflow.com/questions/60221295/getting-parent-child-hierarchy

标签

hierarchy

adjacency-list

mariadb-10.4