如何在sql / oracle中选择节点的所有子级和父级

Question

我有一个如下表

MyTable

| ID     |  PARENT_ID |
-----------------------------
|   20      | null      |
|   40     | null      |
|   50     | null      |
|   70     | 122       |
|   100    | 40        |
|   102    | 4         |
|   126    | 100       |
|   9     | 50         |
|   122    | 40        |
|   123    | 9         | 

我要为给定的三个孩子126，70和123选择包括所有孩子和父对象的层次树

预期产量

| ID     |  PARENT_ID |
-----------------------------
|   126     | 100      |
|   100     | 40       |
|   40      | null     |
|   70      | 122      |
|   122     | 40       |
|   123     | 9        |
|   9       | 50       |
|   50      | null     |

我尝试过

select ID, PARENT_ID
from MyTable
start with ID=126 //this for example 
connect by prior ID=Parent;

Answer 1

You can do it with hierarchical query using CONNECT BY PRIOR clause:

select * from MyTable start with id in (126,70,123)
         connect by prior parent_id = id;

NOTE: Since you have two nodes with parent_id = 40, you will get two rows with 40 as ID and null as parent_id. If you want to leave only one row, use distinct clause:

select distinct * from MyTable start with id in (126,70,123)
         connect by prior parent_id = id;