MySQL find all parents recursively [duplicate] - mysql

Question

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get a recursive parent list
(2 answers)
Closed 8 years ago.
I have the following tables:
Category
id INT
name VARCHAR
Category_parent
category_id INT
parent_id INT
In Category_parent I store category relationship, and both columns get id from category table. So I can identify what is parent of what.
There can be any number of generations, so it is a bit difficult to find all categories from which a particular category inherited.
For example, CAT10's parent is CAT5, CAT5's CAT3, CAT3's CAT1 and so on. Besides, one category may have any number of parents.
I give just name of category and my query should return all ancestors of that category.
Is there a solution to such problems in MySQL? How can I use stored procedure for this?

Answer 1

Let me give you an idea. Create a function that gets the parent_id from a given ID a number of times, let's call it generation. Cat10 generation 1 would be parent who is CAT5 generation 2 would be CAT3 and so on.
DROP FUNCTION IF EXISTS getNameIdGeneration;
DELIMITER $$
CREATE FUNCTION getNameIdGeneration(idPar int, generationPar int)
RETURNS VARCHAR(1000) READS SQL DATA
BEGIN
DECLARE auxLoopVar INT default 0;
DECLARE parentIdVar INT default idPar;
DECLARE nameVar VARCHAR(1000) default NULL;
count_loop: LOOP
SELECT parent_id INTO parentIdVar FROM Category_parent WHERE Category_id = parentIdVar;
SET auxLoopVar = auxLoopVar + 1;
IF auxLoopVar >= generationPar THEN
LEAVE count_loop;
END IF;
END LOOP;
SELECT name INTO nameVar FROM Category WHERE id = parentIdVar;
RETURN nameVar;
END;
$$
DELIMITER ;
assuming that Category_Id for CAT10 = 10 if you test the function given
select getNameIdGeneration(10, 2);
CAT3
Now all you need is a table which contains the id of the CAT you want to know its lineage
MariaDB [mydatabase]> select * from test;
+-------------+------------+
| category_id | generation |
+-------------+------------+
| 10 | 1 |
| 10 | 2 |
| 10 | 3 |
+-------------+------------+
MariaDB [mydatabase]> select generation, getNameIdGeneration(category_id, generation) as Name from test;
+------------+------+
| generation | Name |
+------------+------+
| 1 | CAT5 |
| 2 | CAT3 |
| 3 | CAT1 |
+------------+------+
3 rows in set (0.00 sec)