Question

我有一个表列Id和EmployeeID。表数据具有以下特点：在某些部分（Id是连续的），有时可以找到相同的EmployeeID，例如

Id | EmployeeID
---------------
1  |     1
2  |     1
3  |     2
4  |     5
5  |     1
6  |     1

我想构建一个查询来查找包含相同EmployeeID的数据块，其中Id是连续的（最小值为x记录）。到目前为止，我提出了：

SELECT EmployeeID, MIN(Id), MAX(Id), COUNT(*)
FROM recs
GROUP BY EmployeeID
HAVING COUNT(*) > 5 AND
       MAX(Id) - MIN(Id) + 1 = COUNT(*)

此查询将为我提供一些（但不是全部）数据块，只要同一个Employee只能在一个块中找到。任何人都可以提出一个解决方案，为每位员工提供所有不同的数据块吗？

Answer 1

加入同一个表，其中table1.Id = table2.Id + 1和table1.employeeid = table2.employeeid

Answer 2

不是最好的解决方案，但它应该有效（例如，3个连续的ID）：

SELECT Id, EmployeeID FROM
(
SELECT r.Id, r.EmployeeID, 
(SELECT COUNT(1) FROM recs r1 WHERE (r1.EmployeeID = r.EmployeeID AND r1.id = r.Id-1) AS c1,
(SELECT COUNT(1) FROM recs r2 WHERE (r2.EmployeeID = r.EmployeeID AND r2.id = r.Id-2) AS c2,
(SELECT COUNT(1) FROM recs r3 WHERE (r3.EmployeeID = r.EmployeeID AND r3.id = r.Id-3) AS c3
FROM recs r1) tab1
WHERE (tab1.c1+tab1.c2+tab1.c3 =3);

我建议Id是主要（或唯一）密钥。如果不是，你应该将每个子查询改为SELECT IF（COUNT（1）＆gt; 0,1,0）......

Answer 3

使用临时表。使用此解决方案：

SELECT EmployeeID, MIN(Id) AS Min, MAX(Id) AS Max, COUNT(*) AS Count
INTO #TempTable
FROM recs
GROUP BY EmployeeID

SELECT * FROM #TempTable WHERE
Count > 5 AND
       Max - Min + 1 = Count

编辑回答

请试试这个：

SELECT * FROM(    
SELECT EmployeeID, MIN(Id) AS min, MAX(Id) AS max, COUNT(*) AS count
    FROM recs
    GROUP BY EmployeeID) AS Table
    WHERE Table.count > 5 AND
           Table.max - Table.min + 1 = Table.count

Answer 4

哇，这是一个真正的脑筋急转弯。我敢肯定这有各种各样的漏洞，但这是一个可能的解决方案。首先是我们的测试数据：

If Exists(Select 1 From INFORMATION_SCHEMA.TABLES Where TABLE_NAME = 'recs')
    DROP TABLE recs
GO
Create Table recs
(
    Id int not null
    , EmployeeId int not null
)
Insert recs(Id, EmployeeId) 
Values (1,1) ,(2,1) ,(3,1) ,(4,2) ,(5,5) ,(6,1) ,(7,1) ,(8,1) ,(10,1)   
    ,(11,1) ,(12,1) ,(13,2) ,(14,2) ,(15,2) ,(16,2)

接下来，您需要一个包含一系列数字的Tally或Numbers表。我只在这一个中放了500个元素，但考虑到数据的大小，你可能需要更多。 Tally表中的最大数字应该大于recs表中的最大ID。

Create Table dbo.Tally(Num int not null)
GO
;With Numbers As
    (
    Select ROW_NUMBER() OVER ( ORDER BY s1.object_id) As Num
    From sys.columns as s1
    )
Insert dbo.Tally(Num)
Select Num
From Numbers
Where Num < 500

现在为实际的解决方案。基本上，我使用一系列CTE来推断连续序列的起点和终点。

; With 
    Employees As 
    (
    Select Distinct EmployeeId 
    From dbo.Recs
    )
    , SequenceGaps As
    (
    Select E.EmployeeId, T.Num, R1.Id 
    From dbo.Tally As T
        Cross Join Employees As E
        Left Join dbo.recs As R1
            On R1.EmployeeId = E.EmployeeId
                And R1.Id = T.Num
    Where T.Num <= (    
        Select Max(R3.Id) 
        From dbo.Recs As R3
            Where R3.EmployeeId = E.EmployeeId
            )
    )
    , EndIds As
    (
    Select S.EmployeeId
        , Case When S1.Id Is Null Then S.Id End As [End]
    From SequenceGaps As S
        Join SequenceGaps As S1
            On S1.EmployeeId = S.EmployeeId
                And S1.Num = (S.Num + 1) 
    Where S.Id Is Not Null
        And S1.Id Is Null
    Union All
    Select S.EmployeeId, Max( Id )
    From SequenceGaps As S
    Where S.Id Is Not Null
    Group By S.EmployeeId
    )
    , SequencedEndIds As
    (
    Select EmployeeId, [End]
        , ROW_NUMBER() OVER (PARTITION BY EmployeeId ORDER BY [End]) As SequenceNum
    From EndIds
    )
    , StartIds As
    (
    Select S.EmployeeId
        , Case When S1.Id Is Null Then S.Id End As [Start]
    From SequenceGaps As S
        Join SequenceGaps As S1
            On S1.EmployeeId = S.EmployeeId
                And S1.Num = (S.Num - 1)
    Where S.Id Is Not Null
        And S1.Id Is Null
    Union All
    Select S.EmployeeId, 1 
    From SequenceGaps As S
    Where S.Id = 1
    )
    , SequencedStartIds As
    (
    Select EmployeeId, [Start]
        , ROW_NUMBER() OVER (PARTITION BY EmployeeId ORDER BY [Start]) As SequenceNum
    From StartIds
    )
    , SequenceRanges As
    (
    Select S1.EmployeeId, Start, [End]
    From SequencedStartIds As S1
        Join SequencedEndIds As S2
            On S2.EmployeeId = S1.EmployeeId
                And S2.SequenceNum = S1.SequenceNum
    )
Select *
From SequenceGaps As SG
Where Exists(
        Select 1
        From SequenceRanges As SR
        Where SR.EmployeeId = SG.EmployeeId
            And SG.Id Between SR.Start And SR.[End]
            And ( SR.[End] - SR.[Start] + 1 ) >= @SequenceSize
        )

使用WHERE子句中的final语句和@SequenceSize，可以控制返回哪些序列。

帮我查找数据块

4 个答案: