循环,直到父值为空

Question

我有两张桌子,tbl_folder:

FOLDER_ID  FOLDER_NAME  PARENT_FOLDER_ID
1           Folder1
2           Folder1.1        1
3           Folder1.2        1
4           Folder1.1.1      2
5           Folder1.1.2      2
6           Folder1.2.1      3
7           Folder1.2.2      3

而且tbl_file:

FILE_ID   FILE_NAME   PARENT_FOLDER_ID    ACTIVITY_ID
1         Abc.txt            5                2
2         PQR.txt            2                1
3         XYZ.txt            7                2

我activity_id作为输入传递给一个过程,从中我可以得到该parent_folder_id活动ID的所有文件.我想使用来自的数据获取该父文件夹的完整路径tbl_folder.

例如,如果我传递2,activity_id那么我会得到两个文件:

1. Abc.txt - 文件的父文件夹ID为5
2. XYZ.txt - 文件的父文件夹ID为7

从parent_folder_id我将得到文件夹的名称,例如Folder1.1.2.我将选择该文件夹parent_folder_id并获取其名称和父级,依此类推.最后我将为Abc.txtas 生成路径Folder1\Folder1.1\Folder1.1.2.

这样做的正确方法是什么？我应该使用循环吗？还是一张临时桌子？或者是其他东西？

Answer 1

您可以使用分层查询来获取每个文件夹的完整路径:

select folder_id, sys_connect_by_path(folder_name, '/') as path
from tbl_folder
start with parent_folder_id is null
connect by parent_folder_id = prior folder_id;

 FOLDER_ID PATH                                   
---------- ----------------------------------------
         1 /Folder1                                
         2 /Folder1/Folder1.1                      
         4 /Folder1/Folder1.1/Folder1.1.1          
         5 /Folder1/Folder1.1/Folder1.1.2          
         3 /Folder1/Folder1.2                      
         6 /Folder1/Folder1.2/Folder1.2.1          
         7 /Folder1/Folder1.2/Folder1.2.2       

该sys_connect_by_path功能正在为您构建完整路径.

您可以加入tbl_file到您的文件中以获取每个文件的完整路径:

select f.file_name, h.path
from tbl_file f
join (
  select folder_id, sys_connect_by_path(folder_name, '/') as path
  from tbl_folder
  start with parent_folder_id is null
  connect by parent_folder_id = prior folder_id
) h
on h.folder_id = f.parent_folder_id
where f.activity_id = 2;

FILE_NAME  PATH                                   
---------- ----------------------------------------
Abc.txt    /Folder1/Folder1.1/Folder1.1.2          
XYZ.txt    /Folder1/Folder1.2/Folder1.2.2          

或者使用反斜杠并且根文件夹上没有前导斜杠(可以删除)ltrim(),这更接近您在问题中的示例:

select f.file_name, ltrim(h.path, '\') as path
from tbl_file f
join (
  select folder_id, sys_connect_by_path(folder_name, '\') as path
  from tbl_folder
  start with parent_folder_id is null
  connect by parent_folder_id = prior folder_id
) h
on h.folder_id = f.parent_folder_id
where f.activity_id = 2;

FILE_NAME  PATH                                   
---------- ----------------------------------------
Abc.txt    Folder1\Folder1.1\Folder1.1.2           
XYZ.txt    Folder1\Folder1.2\Folder1.2.2           

在Oracle的更高版本中,您还可以使用递归子查询因子,但在10g中不可用.