Question

我正在尝试编写一个SQL Server查询，其中特定ID可以有多个修订，但我只想提取起始状态和当前/结束状态。我不一定关心沿途发生的事情。

以下是当前数据库结构的示例（我不能假设数据将被排序）。

ID     REV    STATUS    CURRENT      NOTES
----------------------------------------------
1111    1     High       F        Note One
1111    2     High       F        Note Two
1111    3     Medium     F        Note Three
1111    4     Medium     F        Note Four
1111    5     Medium     F        Note Five
1111    6     Medium     F        Note Six
1111    7     Complete   T        Note Seven
2222    1     Medium     F        Note One
2222    2     High       F        Note Two
2222    3     Complete   T        Note Three
3333    1     Low        T        Note One
4444    1     Low        F        Note One
4444    2     Medium     T        Note Two

这是我想要的输出。

ID      START STATUS      END STATUS     END NOTE
---------------------------------------------------
1111    High              Complete       Note Seven
2222    Medium            Complete       Note Three
3333    Low               Low            Note One
4444    Low               Medium         Note Two

非常感谢任何帮助。

Answer 1

起初我以为你只想要第一行和最后一行而且我没有注意到current列......

    select * from 
        (
        select *
            row_number() over (partition by id order by rev asc) rnA,
            row_number() over (partition by id order by rev desc) rnD
        from <table> revs
        ) r
    where rnA = 1 or rnD = 1

实际上在仔细阅读问题之后......

select
    id,
    min(case when rev = 1 then status end) as "Start Status",
    min(case when current = 'T' then status end) as "End Status",
    min(case when current = 'T' then status end) as "End Note"
from <table> rev
group by id

Answer 2

您似乎只需要获取当前修订版的所有行，然后添加第一个修订版的状态。这是一种方式：

SELECT ID, 
    (SELECT [STATUS] FROM MyTable t2 WHERE t2.ID = MyTable.ID AND t2.REV = 1) AS [START STATUS],
    [STATUS] AS [END STATUS], NOTES AS [END NOTE]
FROM MyTable
WHERE [CURRENT] = 'T'

您也可以加入第一个修订版：

SELECT ID, 
    Rev1.[STATUS] AS [START STATUS],
    [STATUS] AS [END STATUS], NOTES AS [END NOTE]
FROM MyTable 
    INNER JOIN MyTable Rev1
        ON MyTable.ID = Rev1.ID 
            AND Rev1.REV = 1
WHERE MyTable.[CURRENT] = 'T'

Answer 3

select ID,
    iif(REV=1,STATUS,null) [START STATUS],
    iif(maxrev is null,null,STATUS) as [END STATUS],
    iif(maxrev is null,null,NOTES) as [END NOTE]
from <tablename,,> t1
left join (select ID, max(REV) maxrev from <tablename,,> group by ID) t2
    on t1.ID=t2.ID and t1.rev=t2.maxrev
group by ID,
    [START STATUS],
    [END STATUS],
    [END NOTE]

SQL查询捕获启动和结束修订状态

3 个答案: