使用SQL和PHP从不同的引用表中获取层次结构树

我有多个具有类似基本结构的表：

biopsy_p0
id | biopsy_id    | introduced

biopsy_p1
id | biopsy_p0_id | introduced

biopsy_p2
id | biopsy_p1_id | introduced

我的目标是获得依赖关系的树视图

活检\u p0.id->活检\u p1.活检\u p0\u id->活检\u p2.活检\u p1\u id

我试着只使用SQL，但从我的问题中可以看出，我在这方面不是很有经验。到目前为止，我所能找到的一切都是关于层次树的参考文献。但它们总是只使用一个带有内部引用的表

--更新： 我现在用PHP实现了它，这真的不是一个好的解决方案，我希望我能用SQL实现它，以便更好地扩展：

PHP代码：

SQL数据：

---

也许最好有一个层次关系表，通过ID引用另一个存储实际数据的表。。。因此，我只涉及两个表，如果添加新元素，将更加灵活…

让我们从声明键开始：

CREATE TABLE IF NOT EXISTS `biopsy` (
  `id` int(11) unsigned NOT NULL primary key,
  `creation_date` date NOT NULL
) ENGINE=InnoDB AUTO_INCREMENT=228 DEFAULT CHARSET=latin1;

INSERT INTO `biopsy` (`id`, `creation_date`) VALUES
(226, '2015-03-08'),
(227, '2015-03-08');

CREATE TABLE IF NOT EXISTS `biopsy_p0` (
`id` int(11) unsigned NOT NULL primary key,
`biopsy_id` int(11) unsigned NOT NULL,
`introduced` date NOT NULL
) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=latin1;

alter table biopsy_p0 add constraint fk_biopsy
    foreign key (biopsy_id)
    references biopsy (id)
        on update cascade
        on delete cascade;

INSERT INTO `biopsy_p0` (`id`, `biopsy_id`, `introduced`) VALUES
(1, 226, '2014-12-31'),
(2, 226, '2014-12-31'),
(3, 226, '2014-12-31'),
(4, 227, '2015-03-14');

-- violates the f.k. introduced
-- (5, 255, '2015-03-10'),
-- (6, 255, '2015-03-12');

CREATE TABLE IF NOT EXISTS `biopsy_p1` (
  `id` int(11) unsigned NOT NULL primary key,
  `biopsy_p0_id` int(11) unsigned NOT NULL,
  `introduced` date NOT NULL
) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=latin1;

alter table biopsy_p1 add constraint fk_biopsy_p0
    foreign key (biopsy_p0_id)
    references biopsy_p0 (id)
        on update cascade
        on delete cascade;

INSERT INTO `biopsy_p1` (`id`, `biopsy_p0_id`, `introduced`)     
VALUES
(1, 1, '2015-03-18'),
(2, 2, '2015-03-31'),
(3, 1, '2015-03-17'),
(4, 1, '2015-03-18'),
(5, 3, '2015-03-11'),
(6, 2, '2015-03-01');

我建议您根据它们的名称来命名，即不要命名id列id并在模型中的其他地方更改它们的名称。例如：

CREATE TABLE IF NOT EXISTS biopsy (
  biopsy_id int unsigned NOT NULL primary key,
  creation_date date NOT NULL
) ENGINE=InnoDB AUTO_INCREMENT=228 DEFAULT CHARSET=latin1;

但我将把它放在一边。现在我们知道数据是一致的：

select x.id as biopsy_id, x.creation_date
     , y.id as biopsy_p0_id, y.introduced as biopsy_p0_introduction
     , z.id as biopsy_p1_id, z.introduced as biopsy_p1_introduction 
from biopsy as x 
left join biopsy_p0 as y 
    on y.biopsy_id = x.id 
left join biopsy_p1 as z 
    on z.biopsy_p0_id = y.id 
order by x.id, y.id, z.id;

+-----------+---------------+--------------+------------------------+--------------+------------------------+
| biopsy_id | creation_date | biopsy_p0_id | biopsy_p0_introduction | biopsy_p1_id | biopsy_p1_introduction |
+-----------+---------------+--------------+------------------------+--------------+------------------------+
|       226 | 2015-03-08    |            1 | 2014-12-31             |            1 | 2015-03-18             |
|       226 | 2015-03-08    |            1 | 2014-12-31             |            3 | 2015-03-17             |
|       226 | 2015-03-08    |            1 | 2014-12-31             |            4 | 2015-03-18             |
|       226 | 2015-03-08    |            2 | 2014-12-31             |            2 | 2015-03-31             |
|       226 | 2015-03-08    |            2 | 2014-12-31             |            6 | 2015-03-01             |
|       226 | 2015-03-08    |            3 | 2014-12-31             |            5 | 2015-03-11             |
|       227 | 2015-03-08    |            4 | 2015-03-14             |         NULL | NULL                   |
+-----------+---------------+--------------+------------------------+--------------+------------------------+
7 rows in set (0.00 sec)

剩下的仅仅是表示，最好用php来完成

对于您的一般问题，是否最好将结构信息保存在一个表中，我想说，如果您有少量的固定级别，您的解决方案就可以了

对于大量级别，或者如果数字未知，则需要某种递归结构注意，您还需要提出此类问题的方法，现在大多数DBMS:s都有递归公共表表达式，但MySQL没有。你可以用变量来解决某些问题，但很快就会变得一团糟。Troels Arvin的链接集位于：

---

您可能会觉得有用。

将右连接更改为左连接谢谢您的回复。我已经试过了，但它也只给了我尾注。所以只有-Second-levela-Second-levelb等等。您能提供示例数据来说明问题创建表和插入语句吗？我现在为这个问题添加了一个PHP解决方案。但是这真的不好，所以如果有任何想法我可以用SQL来管理它，我将不胜感激！这个结果将数据合并并格式化，与我预期的不同。这肯定比我的解决方案更好。也谢谢你的链接，非常感谢。很高兴它有帮助，在SO和其他地方搜索关于主题的有用术语是嵌套集、物化路径和传递闭包。

CREATE TABLE IF NOT EXISTS `biopsy` (
  `id` int(11) unsigned NOT NULL primary key,
  `creation_date` date NOT NULL
) ENGINE=InnoDB AUTO_INCREMENT=228 DEFAULT CHARSET=latin1;

INSERT INTO `biopsy` (`id`, `creation_date`) VALUES
(226, '2015-03-08'),
(227, '2015-03-08');

CREATE TABLE IF NOT EXISTS `biopsy_p0` (
`id` int(11) unsigned NOT NULL primary key,
`biopsy_id` int(11) unsigned NOT NULL,
`introduced` date NOT NULL
) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=latin1;

alter table biopsy_p0 add constraint fk_biopsy
    foreign key (biopsy_id)
    references biopsy (id)
        on update cascade
        on delete cascade;

INSERT INTO `biopsy_p0` (`id`, `biopsy_id`, `introduced`) VALUES
(1, 226, '2014-12-31'),
(2, 226, '2014-12-31'),
(3, 226, '2014-12-31'),
(4, 227, '2015-03-14');

-- violates the f.k. introduced
-- (5, 255, '2015-03-10'),
-- (6, 255, '2015-03-12');

CREATE TABLE IF NOT EXISTS `biopsy_p1` (
  `id` int(11) unsigned NOT NULL primary key,
  `biopsy_p0_id` int(11) unsigned NOT NULL,
  `introduced` date NOT NULL
) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=latin1;

alter table biopsy_p1 add constraint fk_biopsy_p0
    foreign key (biopsy_p0_id)
    references biopsy_p0 (id)
        on update cascade
        on delete cascade;

INSERT INTO `biopsy_p1` (`id`, `biopsy_p0_id`, `introduced`)     
VALUES
(1, 1, '2015-03-18'),
(2, 2, '2015-03-31'),
(3, 1, '2015-03-17'),
(4, 1, '2015-03-18'),
(5, 3, '2015-03-11'),
(6, 2, '2015-03-01');

CREATE TABLE IF NOT EXISTS biopsy (
  biopsy_id int unsigned NOT NULL primary key,
  creation_date date NOT NULL
) ENGINE=InnoDB AUTO_INCREMENT=228 DEFAULT CHARSET=latin1;

select x.id as biopsy_id, x.creation_date
     , y.id as biopsy_p0_id, y.introduced as biopsy_p0_introduction
     , z.id as biopsy_p1_id, z.introduced as biopsy_p1_introduction 
from biopsy as x 
left join biopsy_p0 as y 
    on y.biopsy_id = x.id 
left join biopsy_p1 as z 
    on z.biopsy_p0_id = y.id 
order by x.id, y.id, z.id;

+-----------+---------------+--------------+------------------------+--------------+------------------------+
| biopsy_id | creation_date | biopsy_p0_id | biopsy_p0_introduction | biopsy_p1_id | biopsy_p1_introduction |
+-----------+---------------+--------------+------------------------+--------------+------------------------+
|       226 | 2015-03-08    |            1 | 2014-12-31             |            1 | 2015-03-18             |
|       226 | 2015-03-08    |            1 | 2014-12-31             |            3 | 2015-03-17             |
|       226 | 2015-03-08    |            1 | 2014-12-31             |            4 | 2015-03-18             |
|       226 | 2015-03-08    |            2 | 2014-12-31             |            2 | 2015-03-31             |
|       226 | 2015-03-08    |            2 | 2014-12-31             |            6 | 2015-03-01             |
|       226 | 2015-03-08    |            3 | 2014-12-31             |            5 | 2015-03-11             |
|       227 | 2015-03-08    |            4 | 2015-03-14             |         NULL | NULL                   |
+-----------+---------------+--------------+------------------------+--------------+------------------------+
7 rows in set (0.00 sec)