如何离开连接或内部连接表本身

Question

例如,我在表格中有这些数据

id      name        parent      parent_id
1       add         self        100
2       manage      null        100
3       add         10          200
4       manage      null        200
5       add         20          300
6       manage      null        300

我怎么能left join或inner join这个表本身所以我得到这个结果？

id      name        parent
2       manage      self
4       manage      10
6       manage      20

正如我所知,我只想用关键字'manage'查询行,但我希望列parent的数据在add的行中作为结果中manage的行.

可能吗？

编辑:

我的实际表的简化版- system,

system_id   parent_id   type    function_name       name        main_parent         make_accessible     sort
31          30          left    main                Main        NULL                0                   1
32          31          left    page_main_add       Add         self                0                   1
33          31          left    page_main_manage    Manage      NULL                0                   2

我的实际查询已经非常混乱......

SELECT 
    a.system_id,
    a.main_parent,
    b.name, 
    b.make_accessible, 
    b.sort

FROM system AS a

INNER JOIN -- self --
(
    SELECT system_id, name, make_accessible, sort
    FROM system AS s2

    LEFT JOIN -- search --
    (
    SELECT system_id AS parent_id
    FROM system AS s1
    WHERE s1.function_name = 'page'
    ) AS s1

    ON s1.parent_id = s2.parent_id

    WHERE s2.parent_id = s1.parent_id
    AND s2.system_id != s1.parent_id
    ORDER BY s2.sort ASC
) b
ON b.system_id = a.parent_id


WHERE a.function_name LIKE '%manage%'
ORDER BY b.sort ASC

我得到的结果,

system_id   main_parent     name    make_accessible sort
33          NULL            Main    0                1

但我在此之后,

system_id   main_parent     name    make_accessible sort
33          self            Main    0                1

Answer 1

您只需要两次引用该表:

select t1.id, t1.name, t2.id, t2.name
from TableA t1 
  inner join TableA t2
    on t1.parent_id = t2.Id

如果要在列表中查看根,请将内部替换为左连接.

更新:

我误解了你的问题.在我看来,你总是有两行,管理一行并添加一行.要从manage获得"添加":

select system.*, (select parent 
                    from system s2 
                   where s2.parent_id = system.parent_id 
                     and s2.name = 'add') 
                 AS parent
from system
where name = 'manage'

或者,您可以将表拆分为两个派生表,并通过parent_id连接它们:

select *
  from system
  inner join
  (
     select * from system where name = 'add'
  ) s2
    on system.parent_id = s2.parent_id
  where system.name = 'manage'

这将允许您使用s2中的所有列.