根据另一列的值显示列

Question

有一个这样的表：

Parent | Child
1      | 11
11     | 12
11     | 13
12     | 14
12     | 14

如果传递1，它应该返回所有'1'孩子的：11,12,13,14

Answer 1

您可以查看使用CTE的递归查询。 关于该主题的链接：

• Simple example of recursive CTE
• Example from MSDN

Answer 2

-- Test data
declare @T table (ParentID int, ChildID int)
insert into @T values(1,       11)
insert into @T values(11,      12)
insert into @T values(11,      13)
insert into @T values(12,      14)
insert into @T values(12,      14)

-- ID to search for
declare @ParentID int = 1

-- Recorsive cte
;with cte as
(
  select T.*
  from @T as T
  where T.ParentID = @ParentID
  union all
  select T.*
  from cte as C
    inner join @T as T
      on C.ChildID = T.ParentID
)
select distinct ChildID
from cte  

结果

ChildID
-------
11
12
13
14