sql-server - 带选项的无限循环 CTE(最大递归 0)

Question

我有一个包含大量记录的 CTE 查询。以前它工作得很好。但最近，它对某些成员抛出错误

The statement terminated. The maximum recursion 100 has been exhausted before statement completion.

因此，我在查询中添加了 OPTION (maxrecursion 0) 或 OPTION (maxrecursion 32767) ，因为我不想限制记录。但是，结果是查询需要永远加载。我该如何解决这个问题？

这是我的代码:

with cte as(
-- Anchor member definition
    SELECT  e.SponsorMemberID , e.MemberID, 1 AS Level
    FROM tblMember AS e 
    where e.memberid = @MemberID

union all

-- Recursive member definition
    select child.SponsorMemberID , child.MemberID, Level + 1
    from tblMember child 

join cte parent

on parent.MemberID = child.SponsorMemberID
)
-- Select the CTE result
    Select distinct a.* 
    from cte a
    option (maxrecursion 0)

编辑:删除不必要的代码以便于理解

已解决:所以问题不是来自 maxrecursion。这是来自 CTE 的。我不知道为什么，但可能它包含任何赞助商周期:A -> B -> C -> A -> ...(感谢@HABO)

这个方法我试过了，有效。 Infinite loop in CTE when parsing self-referencing table

Answer 1

如果您达到了递归限制，则说明您在赞助关系方面具有相当的深度，或者在数据中存在循环。像下面这样的查询将检测循环并终止递归:

declare @tblMember as Table ( MemberId Int, SponsorMemberId Int );
insert into @tblMember ( MemberId, SponsorMemberId ) values
  ( 1, 2 ), ( 2, 3 ), ( 3, 5 ), ( 4, 5 ), ( 5, 1 ), ( 3, 3 );
declare @MemberId as Int = 3;
declare @False as Bit = 0, @True as Bit = 1;

with Children as (
  select MemberId, SponsorMemberId,
    Convert( VarChar(4096), '>' + Convert( VarChar(10), MemberId ) + '>' ) as Path, @False as Loop
    from @tblMember
    where MemberId = @MemberId
  union all
  select Child.MemberId, Child.SponsorMemberId,
    Convert( VarChar(4096), Path + Convert( VarChar(10), Child.MemberId ) + '>' ),
    case when CharIndex( '>' + Convert( VarChar(10), Child.MemberId ) + '>', Path ) = 0 then @False else @True end
    from @tblMember as Child inner join
      Children as Parent on Parent.MemberId = Child.SponsorMemberId
    where Parent.Loop = 0 )
  select *
    from Children
    option ( MaxRecursion 0 );