最大递归已用尽

问题描述 投票:1回答:2

我需要一种有效的方法来传递参数[StartingNumber],并从[StartingNumber]开始依次计数,直到找到一个缺少的数字。

我使用以下sql来获取下一个数字:

      DECLARE @StartOffset int
        SET  @StartOffset = 23
        ; With Missing as (
            select @StartOffset as N where not exists(
    select * from [QUEUE] where QueueNum = @StartOffset AND ismelutash = 1)
        ), Sequence as 
    (       select @StartOffset as N from [QUEUE] where QueueNum = @StartOffset 
            union all
            select b.QueueNum from [QUEUE] b inner join Sequence s 
on b.QueueNum = s.N + 1 and b.ismelutash = 1
        )
        select COALESCE((select N from Missing),(select MAX(N)+1 from Sequence))

它已经工作了一段时间,但是现在当我运行它时,我得到'该语句终止了。语句完成之前已用尽最大递归100。'

有人有什么想法吗?谢谢

编辑:

我添加了maxrecursion,但是它只是加载并且不返回数据:

DECLARE @StartOffset int
SET  @StartOffset = 50

DECLARE @isMelutash int
SET @isMelutash = 0


; With QueueFilters as (
    select queuenum from queue where ismelutash = 1
),  Missing as (
    select @StartOffset as N where not exists(select * from QueueFilters where queuenum = @StartOffset)
), Sequence as (
    select @StartOffset as N from QueueFilters  where queuenum = @StartOffset
    union all
    select b.queuenum from QueueFilters  b inner join Sequence s on b.queuenum = s.N + 1
)
select COALESCE((select N from Missing ),(select MAX(N)+1 from Sequence ) )
**OPTION(MAXRECURSION 150)**
sql sql-server common-table-expression
2个回答
3
投票

您可以在当前代码中使用MAXRECURSION选项

但是,无需逐行递归(使用Itzik Ben-Gan的方法)。这将检测到队列中也没有ismelutash = 1的行的情况,因为它使用Tally表作为参考序列

;WITH
  Pass0 as (select 1 as C union all select 1), --2 rows
  Pass1 as (select 1 as C from Pass0 as A, Pass0 as B),--4 rows
  Pass2 as (select 1 as C from Pass1 as A, Pass1 as B),--16 rows
  Pass3 as (select 1 as C from Pass2 as A, Pass2 as B),--256 rows
  Pass4 as (select 1 as C from Pass3 as A, Pass3 as B),--65536 rows
  Pass5 as (select 1 as C from Pass4 as A, Pass4 as B),--4,294,967,296 rows
  Tally as (select row_number() over(order by C) as Number from Pass5)
 select TOP 1
    Number 
 from 
    Tally T
    LEFT JOIN   --corrected, oops.
    [QUEUE] Q ON T.Number = Q.QueueNum AND Q.ismelutash = 1
 where
    T.Number >= @StartOffset AND T.Number <= 1000000
    AND
    Q.QueueNum IS NULL
 ORDER BY
    T.Number

编辑:

带有MAXRECURSION提示的原始代码末尾This link也更好

      DECLARE @StartOffset int
        SET  @StartOffset = 23
        ; With Missing as (
            select @StartOffset as N where not exists(
    select * from [QUEUE] where QueueNum = @StartOffset AND ismelutash = 1)
        ), Sequence as 
    (       select @StartOffset as N from [QUEUE] where QueueNum = @StartOffset 
            union all
            select b.QueueNum from [QUEUE] b inner join Sequence s 
on b.QueueNum = s.N + 1 and b.ismelutash = 1
        )
        select COALESCE((select N from Missing),(select MAX(N)+1 from Sequence))
        OPTION (MAXRECURSION 0)

2
投票

我相信这是等效的,并且不使用递归:

    SELECT COALESCE(MIN(QueueNum)
        , (SELECT Max(QueueNum) + 1
            FROM [Queue] 
            WHERE QueueNum > @StartOffset)
        , @StartOffset)
    FROM [QUEUE]
    WHERE QueueNum >= @StartOffset
    AND ismelutash != 1
© www.soinside.com 2019 - 2024. All rights reserved.