在递归 SQL 中获取给定段的父母和孩子

Question

给定开头、中间或结尾的 ID，我想查找它们之间链接的所有行。

这样我递归地找到了子元素

declare @T table(
  Id int primary key,
  Name nvarchar(255) not null,
  ParentId int)

insert into @T values
(1,   'A',    NULL),
(2,   'B',    1),
(3,   'C',    2),
(4,   'D',    NULL),
(5,   'E',    1)

declare @Id int = 2

;with cte as
(  
  select T.*
  from @T as T
  where T.Id = @Id
  union all
  select T.*
  from @T as T
    inner join cte as C
      on T.ParentId = C.Id
)
select *
from cte 

如果@Id 等于 2，我将得到 2 和 3。但我也想检索父级，在本例中为 1。

我想得到这个：

如果 id = 1

1 A NULL
2 B 1
3 C 2
5 E 1

如果 id = 2

1 A NULL
2 B 1
3 C 2
5 E 1

如果 id = 3

1 A NULL
2 B 1
3 C 2
5 E 1

如果 id = 4

4 D NULL

如果 id = 5

1 A NULL
2 B 1
3 C 2
5 E 1

我该如何解决这个问题？

Answer 1

好的！我有你：

我创建了一个单独的家庭进行测试。

您需要做的第一件事是创建一个查询来查找您选择的 ID 的最古老的祖先。这是下面的第一个 CTE。然后你指定它，我称之为@Eve 并找到夏娃，夏娃的所有孩子。

Here is the example你可以玩弄

  create table UserType (
  Id int,
   name nvarchar(255),
  parentid int)

insert into UserType values
(1,  'A',    NULL),
(2,  'B',  1),
(3,  'C',   2),
(4,  'D',    NULL),
(5,  'E',   1),
(6,  'F',   NULL),
(7,  'G',      6),
(8,  'H',     7);

DECLARE @eve BIGINT;  --ancestor
DECLARE @id BIGINT;
SET @id = 8;  --This is where you choose

WITH tblParent AS  --CTE for oldest ancestor
(
    SELECT *
        FROM UserType WHERE Id = @id
    UNION ALL
    SELECT UserType.*
        FROM UserType  JOIN tblParent  ON UserType.Id = tblParent.ParentId
)
select
@eve = (select top 1 id from tblParent order by id);

WITH tblChild AS  --CTE for all @eve and all children
(
    SELECT *
        FROM UserType WHERE id = @eve
    UNION ALL
    SELECT UserType.* FROM UserType  JOIN tblChild  ON UserType.ParentId = tblChild.Id
)
SELECT * FROM tblChild
order by id


OPTION(MAXRECURSION 32767)

Props to CodeProject 很有帮助。

Answer 2

试试这样的。

declare  @tbl table( --test table var
Id int,
name nvarchar(255),
parentid int)

insert into @tbl values -- test data
(1,  'A',    NULL),
(2,  'B',  1),
(3,  'C',   2),
(4,  'D',    NULL),
(5,  'E',   1),
(6,  'F',   NULL),
(7,  'G',      6),
(8,  'H',     7);

declare @id int = 7

;with parents as (
select id,name,parentid, 0 lvl
from @tbl 
where id=@id
union all
select t.id,t.name,t.parentid,  lvl-1
from @tbl t
inner join parents p on t.Id=p.parentid --up the tree
)
,children as (
select id,name,parentid, 0 lvl
from @tbl 
where id=@id --select single record
union all
select t.id,t.name,t.parentid,  lvl+1
from @tbl t
inner join children c on c.Id=t.parentid -- down the tree
)
select * from parents
union --combine results
select * from children
order by lvl