如何在MySQL中查找所有子行？

Question

我有一个层次结构系统设置,用于存储数据库中项目的级别和父ID.我想弄清楚的是我将如何找到用户选择的所有子行.以下是表结构的示例:

+----+---------+----------+-------+
| 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 |
+----+---------+----------+-------+

那么,如果有人删除honda,我将如何删除层次结构中的所有内容？数据库只能达到3级.

Answer 1

请参阅使用关系innoDB的递归MySQL查询

我昨天也发了一个答案

更新:

以下是function基于上述链接,但已根据您的DELETE要求量身定制

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)

删除所有条目及其关系 id = 1 honda

希望它有所帮助