其实大家稍微动下大脑,问题可以转化为,是求最小连续数组中的最大值,数组大小可以为1。
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做戏做全套,送佛送到西。
为了便于学习研究,必然是要写全套示例代码的。- -------------------------------------------------------------------------------------
- --by wls
- --非专业SQL 不求高效 但求能跑
- USE tempdb
- GO
- -------------------------------------------------------------------------------------
- IF OBJECT_ID (N't_MaxInMinContinuousArr', N'U') IS NOT NULL
- DROP TABLE t_MaxInMinContinuousArr;
- GO
- CREATE TABLE t_MaxInMinContinuousArr(SNId INTEGER PRIMARY KEY,SomeDate DATETIME)
- GO
- -------------------------------------------------------------------------------------
- DECLARE @i INT
- SET @i = --SNId起始值
- DECLARE @TestScale INTEGER
- SET @TestScale=+@i --数据规模
- DECLARE @t DATETIME ,
- @t DATETIME ,
- @dd INT ,
- @dayadd INT ,
- @tRes DATETIME
- SET @t = '-- ::'
- SET @t = '-- ::'
- SET @dd = DATEDIFF(dd, @t, @t)
- WHILE @i < @TestScale --数据规模
- BEGIN
- SET @dayadd = @dd * RAND()
- SET @tRes = DATEADD(dd, @dayadd, @t) + RAND()
- INSERT INTO t_MaxInMinContinuousArr VALUES(@i , @tRes)
- SET @i = @i +
- END
- GO
- --SELECT TOP * FROM t_MaxInMinContinuousArr
- --GO
- -------------------------------------------------------------------------------------
- --Delete some SNId randomly
- DECLARE @TestScale INTEGER
- SET @TestScale= --数据规模
- DELETE FROM t_MaxInMinContinuousArr WHERE SNId=--(SELECT abs(checksum(newid()))%@TestScale + )
- DELETE FROM t_MaxInMinContinuousArr WHERE SNId=--(SELECT abs(checksum(newid()))%@TestScale + )
- GO
- --SELECT TOP * FROM t_MaxInMinContinuousArr
- --GO
- -------------------------------------------------------------------------------------
- --now find the SNId that SNId+ is missing.
- WITH TMinAndMaxSNId
- AS(
- SELECT MIN(SNId) AS MinSNId,MAX(SNId) AS MaxSNId FROM t_MaxInMinContinuousArr --The min and max SNId
- ),
- TContinuousId
- AS
- (
- SELECT number AS SNIdCmped FROM master..spt_values,TMinAndMaxSNId WHERE type='p' AND number >=TMinAndMaxSNId.MinSNId AND number <=TMinAndMaxSNId.MaxSNId
- )
- SELECT MIN(res.SNIdCmped)- FROM
- (
- SELECT SNIdCmped FROM TContinuousId
- EXCEPT
- SELECT SNId FROM t_MaxInMinContinuousArr) AS res
- GO
复制代码 附上执行计划
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我也不知道这代码能不能用,先发表了后续慢慢改吧。
网络代码有风险 复制粘贴需谨慎
执行这两个语句清缓存。- DBCC FREEPROCCACHE
- GO
- DBCC DROPCLEANBUFFERS
- GO
复制代码 =======================================================================
20151103-01
代码有问题 有空改
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20151103-02
又尝试了一下(大概几十次猜范围),发现只能处理2048以内的缺失查找。这是个敏感的数字,得研究下。
当然也可能是我不专业,写的代码有问题。
幸好不是我在开发、生产中遇到的问题,还能悠哉悠哉的分析查找问题。
这件事的启示是:你们这些讨人厌的爬虫小网站,错误代码就在这里我还就是不改了。
你们的行为是违法的,并不是说通知然后删除就是可以的。
我保留一切法律赋予我的权利。
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