如何在MySQL中查找所有子行? [英] How to find all child rows in MySQL?

问题描述

我有一个层次结构系统设置程序，用于将项目的级别和父ID存储在数据库中.我要弄清楚的是如何找到用户选择的所有子行.这是表结构的示例:

I have a hierarchy system setup that stores the level and parent ID of the item in a database. What I am trying to figure out is how would I go about finding all the child rows of the one the user select. Here is a sample of the table structure:

+----+---------+----------+-------+
| Id |  label  | parentid | level |
+----+---------+----------+-------+
|  1 | honda   |        0 |     1 |
|  2 | accord  |        1 |     2 |
|  3 | civic   |        1 |     2 |
|  4 | element |        1 |     2 |
|  5 | v4      |        2 |     3 |
|  6 | v6      |        2 |     3 |
+----+---------+----------+-------+

因此，如果有人删除honda，我将如何删除层次结构中的所有内容?数据库只会降到3级.

So, if someone deletes honda, how would I go about deleting everything down the hierarchy? The database will only ever have down to a level 3.

推荐答案

引用，

Refer, Recursive MySQL Query with relational innoDB

我昨天发布了同样的答案

I had posted a answer yesterday for the same

更新:

以下是基于上述链接的function，但已根据您的DELETE要求进行了量身定制

Below is a function based on the above link, but has been tailored for your DELETE requirements

CREATE PROCEDURE `delete_relations`(`_id` INT)
BEGIN
DECLARE  delete_row_ids varchar(200);
DECLARE id, id2 varchar(200);
DECLARE rows_affected int;

SET delete_row_ids  = _id;
SET id              = _id;
SET id2             = id;

WHILE id2 IS NOT NULL DO 
    SET id = NULL;
    SELECT GROUP_CONCAT( hierarchical_data.id ), CONCAT( GROUP_CONCAT( hierarchical_data.ID ),',',delete_row_ids) INTO id, delete_row_ids FROM hierarchical_data WHERE FIND_IN_SET( parentid , id2 ) GROUP BY parentid ;
    SET id2 = id;
END WHILE;  

DELETE FROM hierarchical_data where FIND_IN_SET(hierarchical_data.id, delete_row_ids);
SELECT row_count() INTO rows_affected;

if rows_affected > 0 THEN
SELECT delete_row_ids as row_ids_deleted;
ELSE
SELECT 'NO_ROWS_DELETED';
END IF;

END//

SQLFiddle

使用

CALL delete_relations(1)

删除id = 1 honda

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