多次选择同一行

Question

我有一个表有一个主对象的孩子.任何子项都可以出现多次,并且有一个包含该数字的Occurences列,因此表中的数据类似于:

ChildID | ParentID | Occurences
-------------------------------
      1 |        1 |        2
      2 |        1 |        2
      3 |        2 |        1
      4 |        2 |        3

我需要得到所有孩子的清单,每个孩子在结果中出现核心次数,例如

IDENT | ChildID | ParentID
--------------------------
    1 |       1 |        1
    2 |       1 |        1
    3 |       2 |        1
    4 |       2 |        1
    5 |       3 |        2
    6 |       4 |        2
    7 |       4 |        2
    8 |       4 |        2

我可以使用一个循环表的游标并插入尽可能多的行,但我认为这不是最好的解决方案.

谢谢您的帮助

---

创建脚本包括:

DECLARE @Children TABLE (ChildID int, ParentID int, Occurences int)

INSERT  @Children
SELECT  1, 1, 2 UNION ALL
SELECT  2, 1, 2 UNION ALL
SELECT  3, 2, 1 UNION ALL
SELECT  4, 2, 3

Answer 1

;with C as
(
  select ChildID,
         ParentID,
         Occurences - 1 as Occurences
  from @Children
  union all
  select ChildID,
         ParentID,
         Occurences - 1 as Occurences
  from C
  where Occurences > 0
)
select row_number() over(order by ChildID) as IDENT,
       ChildID,
       ParentID
from C
order by IDENT