Sql 文件系统中目录路径的分层/树数据库_Sql_Sqlite_Path_Tree_Hierarchical Data

Sql 文件系统中目录路径的分层/树数据库

sql sqlite path tree

Sql 文件系统中目录路径的分层/树数据库,sql,sqlite,path,tree,hierarchical-data,Sql,Sqlite,Path,Tree,Hierarchical Data,我想将目录（存在于磁盘上）存储到数据库中，保持它们的层次/树结构这是一个数字： (ROOT) / \ Dir2 Dir3 / \ \ Dir4 Dir5 Dir6 / Dir7 （根

我想将目录（存在于磁盘上）存储到数据库中，保持它们的层次/树结构

这是一个数字：

(ROOT) / \ Dir2 Dir3 / \ \ Dir4 Dir5 Dir6 / Dir7 （根） / \ Dir2 Dir3 / \ \ Dir4 Dir5 Dir6 / 迪尔7 我正在使用SQLite数据库

请建议我：

在SQLite数据库中存储上述结构的SQL查询，以及

当我选择一个目录时检索该目录的完整路径的查询

i、 e.假设我选择

Dir7

，那么我应该得到完整的路径，如

ROOT/Dir2/Dir4/Dir7

将层次结构数据表示为一系列节点，每个节点都有一个ID和一个父ID。您可以将文件存储在一个名为DIRTAB的表中，该表有两个ID列，其中一个列用于单个目录名的文本：

ID -- as a primary key  
PARENT_ID -- refers to the ID of the parent row in DIRTAB  
DIRNAME -- the text of the name eg Dir5

SQLite缺少CONNECT BY子句，即Oracle必须处理分层数据，但我认为，如果您准备接受一些难看的SQL，您可以近似使用分层数据：

SELECT (CASE WHEN p5.DIRNAME IS NOT NULL THEN p5.DIRNAME || '/' ELSE '' END) ||
       (CASE WHEN p4.DIRNAME IS NOT NULL THEN p4.DIRNAME || '/' ELSE '' END) ||
       (CASE WHEN p3.DIRNAME IS NOT NULL THEN p3.DIRNAME || '/' ELSE '' END) ||
       (CASE WHEN p2.DIRNAME IS NOT NULL THEN p2.DIRNAME || '/' ELSE '' END) ||
       (CASE WHEN p1.DIRNAME IS NOT NULL THEN p1.DIRNAME || '/' ELSE '' END) ||
       p0.DIRNAME as FULLPATH
FROM DIRTAB p0
     LEFT OUTER JOIN DIRTAB p1 ON p1.ID = p0.PARENT_ID
     LEFT OUTER JOIN DIRTAB p2 ON p2.ID = p1.PARENT_ID
     LEFT OUTER JOIN DIRTAB p3 ON p3.ID = p2.PARENT_ID
     LEFT OUTER JOIN DIRTAB p4 ON p4.ID = p3.PARENT_ID
     LEFT OUTER JOIN DIRTAB p5 ON p5.ID = p4.PARENT_ID
WHERE p0.DIRNAME = 'Dir6'

这里的问题是，您必须预测目录结构的最大深度，并扩展SQL语句以应对这种情况。例如，我已经完成了6个级别。

我还假设SQLite连接空字符串没有问题。（一些数据库将它们视为null，并将整个表达式结果转换为null）

下面是一个SQLite的快速闭包表示例。我还没有包括将项插入现有树的语句。相反，我只是手动创建了这些语句。您可以在幻灯片中找到insert和delete语句

为了在插入目录ID时保持理智，我重命名了目录以匹配其ID：

        (ROOT)
      /        \ 
    Dir2        Dir3
    /    \           \
  Dir4   Dir5        Dir6
  /          
Dir7

创建表格

CREATE TABLE `filesystem` (
  `id` INTEGER,
  `dirname` TEXT,
  PRIMARY KEY (`id`)
);

CREATE TABLE `tree_path` (
  `ancestor` INTEGER,
  `descendant` INTEGER,
  PRIMARY KEY (`ancestor`, `descendant`)
);

INSERT INTO tree_path (ancestor, descendant) VALUES (1, 1);
INSERT INTO tree_path (ancestor, descendant) VALUES (1, 2);
INSERT INTO tree_path (ancestor, descendant) VALUES (1, 3);
INSERT INTO tree_path (ancestor, descendant) VALUES (1, 4);
INSERT INTO tree_path (ancestor, descendant) VALUES (1, 5);
INSERT INTO tree_path (ancestor, descendant) VALUES (1, 6);
INSERT INTO tree_path (ancestor, descendant) VALUES (1, 7);
INSERT INTO tree_path (ancestor, descendant) VALUES (2, 2);
INSERT INTO tree_path (ancestor, descendant) VALUES (2, 4);
INSERT INTO tree_path (ancestor, descendant) VALUES (2, 5);
INSERT INTO tree_path (ancestor, descendant) VALUES (2, 7);
INSERT INTO tree_path (ancestor, descendant) VALUES (3, 3);
INSERT INTO tree_path (ancestor, descendant) VALUES (3, 6);
INSERT INTO tree_path (ancestor, descendant) VALUES (4, 4);
INSERT INTO tree_path (ancestor, descendant) VALUES (4, 7);
INSERT INTO tree_path (ancestor, descendant) VALUES (5, 5);
INSERT INTO tree_path (ancestor, descendant) VALUES (6, 6);
INSERT INTO tree_path (ancestor, descendant) VALUES (7, 7);

# (ROOT) and subdirectories
SELECT f.id, f.dirname FROM filesystem f
  JOIN tree_path t
    ON t.descendant = f.id
 WHERE t.ancestor = 1;

+----+---------+
| id | dirname |
+----+---------+
|  1 | ROOT    |
|  2 | Dir2    |
|  3 | Dir3    |
|  4 | Dir4    |
|  5 | Dir5    |
|  6 | Dir6    |
|  7 | Dir7    |
+----+---------+


# Dir3 and subdirectories
SELECT f.id, f.dirname
  FROM filesystem f
  JOIN tree_path t
    ON t.descendant = f.id
 WHERE t.ancestor = 3;

+----+---------+
| id | dirname |
+----+---------+
|  3 | Dir3    |
|  6 | Dir6    |
+----+---------+

# Dir5 and parent directories
SELECT f.id, f.dirname
  FROM filesystem f
  JOIN tree_path t
    ON t.ancestor = f.id
 WHERE t.descendant = 5;

+----+---------+
| id | dirname |
+----+---------+
|  1 | ROOT    |
|  2 | Dir2    |
|  5 | Dir5    |
+----+---------+

# Dir7 and parent directories
SELECT f.id, f.dirname
  FROM filesystem f
  JOIN tree_path t
    ON t.ancestor = f.id
 WHERE t.descendant = 7;

+----+---------+
| id | dirname |
+----+---------+
|  1 | ROOT    |
|  2 | Dir2    |
|  4 | Dir4    |
|  7 | Dir7    |
+----+---------+

SELECT f.id, f.dirname
  FROM filesystem f
  JOIN tree_path t
    ON t.ancestor = f.id
 WHERE t.descendant = (
SELECT id
  FROM filesystem
 WHERE dirname LIKE '%7%'
);

+----+---------+
| id | dirname |
+----+---------+
|  1 | ROOT    |
|  2 | Dir2    |
|  4 | Dir4    |
|  7 | Dir7    |
+----+---------+

将目录插入
文件系统
表

INSERT INTO filesystem (id, dirname) VALUES (1, 'ROOT');
INSERT INTO filesystem (id, dirname) VALUES (2, 'Dir2');
INSERT INTO filesystem (id, dirname) VALUES (3, 'Dir3');
INSERT INTO filesystem (id, dirname) VALUES (4, 'Dir4');
INSERT INTO filesystem (id, dirname) VALUES (5, 'Dir5');
INSERT INTO filesystem (id, dirname) VALUES (6, 'Dir6');
INSERT INTO filesystem (id, dirname) VALUES (7, 'Dir7');

创建闭包表路径

CREATE TABLE `filesystem` (
  `id` INTEGER,
  `dirname` TEXT,
  PRIMARY KEY (`id`)
);

CREATE TABLE `tree_path` (
  `ancestor` INTEGER,
  `descendant` INTEGER,
  PRIMARY KEY (`ancestor`, `descendant`)
);

INSERT INTO tree_path (ancestor, descendant) VALUES (1, 1);
INSERT INTO tree_path (ancestor, descendant) VALUES (1, 2);
INSERT INTO tree_path (ancestor, descendant) VALUES (1, 3);
INSERT INTO tree_path (ancestor, descendant) VALUES (1, 4);
INSERT INTO tree_path (ancestor, descendant) VALUES (1, 5);
INSERT INTO tree_path (ancestor, descendant) VALUES (1, 6);
INSERT INTO tree_path (ancestor, descendant) VALUES (1, 7);
INSERT INTO tree_path (ancestor, descendant) VALUES (2, 2);
INSERT INTO tree_path (ancestor, descendant) VALUES (2, 4);
INSERT INTO tree_path (ancestor, descendant) VALUES (2, 5);
INSERT INTO tree_path (ancestor, descendant) VALUES (2, 7);
INSERT INTO tree_path (ancestor, descendant) VALUES (3, 3);
INSERT INTO tree_path (ancestor, descendant) VALUES (3, 6);
INSERT INTO tree_path (ancestor, descendant) VALUES (4, 4);
INSERT INTO tree_path (ancestor, descendant) VALUES (4, 7);
INSERT INTO tree_path (ancestor, descendant) VALUES (5, 5);
INSERT INTO tree_path (ancestor, descendant) VALUES (6, 6);
INSERT INTO tree_path (ancestor, descendant) VALUES (7, 7);

# (ROOT) and subdirectories
SELECT f.id, f.dirname FROM filesystem f
  JOIN tree_path t
    ON t.descendant = f.id
 WHERE t.ancestor = 1;

+----+---------+
| id | dirname |
+----+---------+
|  1 | ROOT    |
|  2 | Dir2    |
|  3 | Dir3    |
|  4 | Dir4    |
|  5 | Dir5    |
|  6 | Dir6    |
|  7 | Dir7    |
+----+---------+


# Dir3 and subdirectories
SELECT f.id, f.dirname
  FROM filesystem f
  JOIN tree_path t
    ON t.descendant = f.id
 WHERE t.ancestor = 3;

+----+---------+
| id | dirname |
+----+---------+
|  3 | Dir3    |
|  6 | Dir6    |
+----+---------+

# Dir5 and parent directories
SELECT f.id, f.dirname
  FROM filesystem f
  JOIN tree_path t
    ON t.ancestor = f.id
 WHERE t.descendant = 5;

+----+---------+
| id | dirname |
+----+---------+
|  1 | ROOT    |
|  2 | Dir2    |
|  5 | Dir5    |
+----+---------+

# Dir7 and parent directories
SELECT f.id, f.dirname
  FROM filesystem f
  JOIN tree_path t
    ON t.ancestor = f.id
 WHERE t.descendant = 7;

+----+---------+
| id | dirname |
+----+---------+
|  1 | ROOT    |
|  2 | Dir2    |
|  4 | Dir4    |
|  7 | Dir7    |
+----+---------+

SELECT f.id, f.dirname
  FROM filesystem f
  JOIN tree_path t
    ON t.ancestor = f.id
 WHERE t.descendant = (
SELECT id
  FROM filesystem
 WHERE dirname LIKE '%7%'
);

+----+---------+
| id | dirname |
+----+---------+
|  1 | ROOT    |
|  2 | Dir2    |
|  4 | Dir4    |
|  7 | Dir7    |
+----+---------+

运行一些查询

CREATE TABLE `filesystem` (
  `id` INTEGER,
  `dirname` TEXT,
  PRIMARY KEY (`id`)
);

CREATE TABLE `tree_path` (
  `ancestor` INTEGER,
  `descendant` INTEGER,
  PRIMARY KEY (`ancestor`, `descendant`)
);

INSERT INTO tree_path (ancestor, descendant) VALUES (1, 1);
INSERT INTO tree_path (ancestor, descendant) VALUES (1, 2);
INSERT INTO tree_path (ancestor, descendant) VALUES (1, 3);
INSERT INTO tree_path (ancestor, descendant) VALUES (1, 4);
INSERT INTO tree_path (ancestor, descendant) VALUES (1, 5);
INSERT INTO tree_path (ancestor, descendant) VALUES (1, 6);
INSERT INTO tree_path (ancestor, descendant) VALUES (1, 7);
INSERT INTO tree_path (ancestor, descendant) VALUES (2, 2);
INSERT INTO tree_path (ancestor, descendant) VALUES (2, 4);
INSERT INTO tree_path (ancestor, descendant) VALUES (2, 5);
INSERT INTO tree_path (ancestor, descendant) VALUES (2, 7);
INSERT INTO tree_path (ancestor, descendant) VALUES (3, 3);
INSERT INTO tree_path (ancestor, descendant) VALUES (3, 6);
INSERT INTO tree_path (ancestor, descendant) VALUES (4, 4);
INSERT INTO tree_path (ancestor, descendant) VALUES (4, 7);
INSERT INTO tree_path (ancestor, descendant) VALUES (5, 5);
INSERT INTO tree_path (ancestor, descendant) VALUES (6, 6);
INSERT INTO tree_path (ancestor, descendant) VALUES (7, 7);

# (ROOT) and subdirectories
SELECT f.id, f.dirname FROM filesystem f
  JOIN tree_path t
    ON t.descendant = f.id
 WHERE t.ancestor = 1;

+----+---------+
| id | dirname |
+----+---------+
|  1 | ROOT    |
|  2 | Dir2    |
|  3 | Dir3    |
|  4 | Dir4    |
|  5 | Dir5    |
|  6 | Dir6    |
|  7 | Dir7    |
+----+---------+


# Dir3 and subdirectories
SELECT f.id, f.dirname
  FROM filesystem f
  JOIN tree_path t
    ON t.descendant = f.id
 WHERE t.ancestor = 3;

+----+---------+
| id | dirname |
+----+---------+
|  3 | Dir3    |
|  6 | Dir6    |
+----+---------+

# Dir5 and parent directories
SELECT f.id, f.dirname
  FROM filesystem f
  JOIN tree_path t
    ON t.ancestor = f.id
 WHERE t.descendant = 5;

+----+---------+
| id | dirname |
+----+---------+
|  1 | ROOT    |
|  2 | Dir2    |
|  5 | Dir5    |
+----+---------+

# Dir7 and parent directories
SELECT f.id, f.dirname
  FROM filesystem f
  JOIN tree_path t
    ON t.ancestor = f.id
 WHERE t.descendant = 7;

+----+---------+
| id | dirname |
+----+---------+
|  1 | ROOT    |
|  2 | Dir2    |
|  4 | Dir4    |
|  7 | Dir7    |
+----+---------+

SELECT f.id, f.dirname
  FROM filesystem f
  JOIN tree_path t
    ON t.ancestor = f.id
 WHERE t.descendant = (
SELECT id
  FROM filesystem
 WHERE dirname LIKE '%7%'
);

+----+---------+
| id | dirname |
+----+---------+
|  1 | ROOT    |
|  2 | Dir2    |
|  4 | Dir4    |
|  7 | Dir7    |
+----+---------+

我认为您应该阅读有关caled修改的前序树遍历的方法：
该链接讨论了将层次数据存储到关系数据库中的两种方法：邻接列表模型和改进的前序树遍历算法
改进的前序树遍历方法的主要思想是用指针注释所有节点，以辅助导航和子树选择：
闭包表可能是一个不错的选择。请看一看，也可以看到SQLite mainling列表中再次出现了关于该主题的幻灯片，Eduardo Morras（re）指出了SQLite vtable扩展，用于处理SQLite repo本身的层次结构：1）2）@JOHN:对不起，但我从未使用orientDB，约翰：我不知道你是什么意思，你能举个例子吗？我先读了这些查询，一直在想，“这是怎么回事？”我意识到你的
树路径
表是目录图传递闭包的邻接列表表示，回答了问题，“这条路径是另一条路径的可到达后代吗？”和“这条路径是另一条路径的可到达祖先吗？”？“很好。@seh：是的，这是一种非常好的技术。虽然它比简单的邻接列表需要更多的条目，但选择数据的查询要简单得多。但是我不能接受这个荣誉。如果你想了解更多，请查看我在问题下方评论中发布的比尔·卡温链接。请注意，您还可以添加路径长度，这使得查找直接祖先/后代更简单。
树路径
表不应该包含“嵌套级别”或“深度”字段以使其成为闭包表吗？