sql-server - 用于显示数据更改历史记录的 SQL 查询

Question

我在 SQL Server 数据库中有一个表，它每天存储历史数据。结构如下图所示:

UploadDate    TypeID    Value1   Value2
-------------------------------------------
2012-01-08    1         NEG      1998-02-05
2012-01-08    2         NEG      1999-02-09
2012-01-08    3         STABLE   1997-02-06
2012-02-08    1         NEG      1998-02-05
2012-02-08    2         NEG      1999-02-09
2012-03-08    1         POS      2012-03-08
2012-03-08    2         STABLE   2012-01-08

正如您在上面看到的 TypeID 1 & 2, Value1和 Value2已于 2012-03-08 更改

我的要求是我必须只显示那些从以前的值改变的行。

在这种情况下，因为 TypeID 1 和 2 已更改而不是应显示当前和最接近的先前值。而对于 TypeID 3 因为它没有改变，它只会显示最新的值。结果集如下所示:

UploadDate    TypeID    Value1   Value2
-------------------------------------------
2012-01-08    3         STABLE   1997-02-06
2012-02-08    1         NEG      1998-02-05
2012-02-08    2         NEG      1999-02-09
2012-03-08    1         POS      2012-03-08
2012-03-08    2         STABLE   2012-01-08

知道如何使用 SQL 解决这个问题吗？

Answer 1

Uninspired 版本在有序集合上使用自连接来检查按时间顺序排列的相同 typeid 的前一行的值。如果没有前一行或值不同，则输出该行。

; with numbered as (
  select *,
         row_number() over (order by typeid, uploaddate) rn
    from table1
)
select n1.*
  from numbered n1
  left join numbered n2
    on n1.TypeID = n2.TypeID
   and n1.rn + 1 = n2.rn
 where (n2.rn is null 
    or n1.value1 <> n2.value1
    or n1.value2 <> n2.value2)
 order by typeid, uploaddate

Here is Sql Fiddle with example .

更新 : 另一个不需要自加入但需要分组的变体。相同 typeid、value1 和 value2 的每个时间线都被赋予唯一的 group_number，稍后用于提取组的 max(uploaddate)。

; with numbered as (
  select *,
         row_number() over (order by typeid, uploaddate)
       - row_number() over (partition by typeid, value1, value2 
                            order by uploaddate) group_number
    from table1
)
select max(uploaddate) uploaddate, typeid, value1, value2
  from numbered
group by typeid, value1, value2, group_number
order by typeid, uploaddate

Another Sql Fiddle .