返回使用遞歸CTE的所有非葉子節點MS SQL

Question

我有一個數據

id  name  mgtId 
-------------------------- 
1  joe   null 
2  jack   1 
3  jill   1 
4  paul   2 
5  ron   4 
6  sam   2 

mgtId引用編號的表。我如何使用CTE選擇非葉節點（joe，jack，paul）。

Answer 1

select * 
from table 
where id in (select mgtId from table) 

Answer 2

方式一：

;with parents_id as (
    select distinct mgtId as id 
    from your_table 
) 
select * 
from your_table t 
inner join parants_id p on t.id = p.id 

修訂 25 APRL 2012

我來test above query和它的工作原理，並返回根節點：

select * 
into #your_table 
from (
select 1 as id, 'joe' as name, null as mgtId union all 
select 2,  'jack ',  1 union all 
select 3,  'jill ' ,  1 union all 
select 4,  'paul ' ,  2 union all 
select 5,  'ron ' ,  4 union all 
select 6,  'sam' ,  2 ) T 


;with parents_id as (
    select distinct mgtId as id 
    from #your_table 
) 
select * 
from #your_table t 
inner join parents_id p on t.id = p.id 

結果：

id name mgtId id 
-- ------- ----- -- 
1 joe  null 1 
2 jack 1  2 
4 paul 2  4 

Answer 3

與CTE爲（ 選擇ID，從mgtId mgr_emp ） 選擇b.id，b.name，b.mgtId，a.mgtId從CTE右連接mgr_emp b 上b.mgtId =一.id