查找连续序列并建议序列中的下一个数字

Posted 2023-03-31

【中文标题】查找连续序列并建议序列中的下一个数字

【英文标题】：Find consecutive sequence and suggest next number in sequence

【发布时间】：2021-12-09 15:52:33

【问题描述】：

我正在尝试创建一个程序，它将：

将任何数字作为输入，例如102 找到它所属的序列范围，例如100 to 103 向用户返回建议的下一个号码，例如104

表格本身看起来像这样：

Num
100
101
102
103
110
111
112
113
114
115
120
121

理想情况下，查询的输出会返回如下内容：

start	end	nextNr
100	103	104
110	115	116
120	121	122

我正在尝试做的这件事与某种间隙和孤岛技术有关。 我看了看从这里尝试一些东西，但无法让它发挥作用。 Gaps and Islands Link

这是我尝试过的……

WITH cteSource(ID, Seq, Num)
AS(
    SELECT d.ID, f.Seq, f.Num
    FROM (
        SELECT 
            ID,
            ROW_NUMBER() OVER (PARTITION BY ID ORDER BY MIN(SeqNo)) AS Grp,
            MIN(SeqNo) AS StartSeqNo,
            MAX(SeqNo) AS EndSeqNo
        FROM
            (
            SELECT 1 ID, Num SeqNo, 
               Num - ROW_NUMBER() OVER (PARTITION BY 1 ORDER BY Num) AS RN
            FROM 
            Number
            ) AS a
        GROUP BY ID, RN
        ) d
    CROSS APPLY (
            VALUES (d.Grp, d.EndSeqNo + 1),(d.Grp -1, d.StartSeqNo -1)
            ) AS f(Seq, Num)
)
SELECT ID, MIN(Num) AS StartSeqNo, MAX(Num) AS EndSeqNo, MAX(Num) + 1 as NextNr
FROM cteSource
GROUP BY ID, Seq
HAVING COUNT(*) = 2

结果如下：

StartSeqNo	EndSeqNo	NextNr
104	109	110
116	119	120

设置如下：

CREATE TABLE [dbo].[Number](
    [Num] [int] NULL
) 
GO

INSERT INTO Number
(Num)
VALUES
(100),
(101),
(102),
(103),
(110),
(111),
(112),
(113),
(114),
(115),
(120),
(121)

【参考方案1】：

也许这会有所帮助。

Select [Start]  = min(num)
      ,[End]    = max(num)
      ,[NextNr] = max(num) + 1
 From (
        Select * 
              ,Grp = num - row_number() over (order by num)
         From  number
      ) A
 Group By Grp

结果

Start   End     NextNr
100     103     104
110     115     116
120     121     122

【讨论】：

这真是……太棒了！

哇，这么简单...我如何确保NextNr 不会意外进入下一个序列？在我发布之后才意识到这可能会发生......

@Justin 如果 NextNr 可以进入下一个序列，这意味着那里没有间隙，并且结果序列看起来不会像那样。

【参考方案2】：

您的第一个子查询可以很好地获取组以及开始和结束编号：

  SELECT 
            ROW_NUMBER() OVER (PARTITION BY ID ORDER BY MIN(SeqNo)) AS Grp,
            MIN(SeqNo) AS StartSeqNo,
            MAX(SeqNo) AS EndSeqNo
        FROM
            (
            SELECT 1 ID, Num SeqNo, 
               Num - ROW_NUMBER() OVER (PARTITION BY 1 ORDER BY Num) AS RN
            FROM 
            Number
            ) AS a
        GROUP BY ID, RN

然后你就不必要地把它复杂化了，而不是仅仅为 NextNr 使用 EndSeqNo + 1：

WITH CTE_Groups AS 
(
        SELECT 
            ROW_NUMBER() OVER (PARTITION BY ID ORDER BY MIN(SeqNo)) AS Grp,
            MIN(SeqNo) AS StartSeqNo,
            MAX(SeqNo) AS EndSeqNo
        FROM
            (
            SELECT 1 ID, Num SeqNo, 
               Num - ROW_NUMBER() OVER (PARTITION BY 1 ORDER BY Num) AS RN
            FROM 
            Number
            ) AS a
        GROUP BY ID, RN
)
SELECT *, EndSeqNo + 1 AS NextNr 
FROM 
CTE_Groups

编辑：并进一步删除不必要的分区和额外的列

WITH CTE_Groups AS 
(
        SELECT 
            MIN(SeqNo) AS StartSeqNo,
            MAX(SeqNo) AS EndSeqNo
        FROM
            (
            SELECT  Num SeqNo, 
               Num - ROW_NUMBER() OVER (ORDER BY Num) AS RN
            FROM 
            Number
            ) AS a
        GROUP BY RN
)
SELECT *, EndSeqNo + 1 AS NextNr 
FROM 
CTE_Groups