如何使用时间戳作为参考合并SQL Server 2014中同一表中的记录

Question

目前，在将PIVOT（）与以下格式和数据值一起使用后，我有一个表

NameID   DocumentName   Time  Value1  Value2  Value3  Value4  Value5
------   ------------   ----  ------  ------  ------  ------  ------
2221        Doc1        1053    23      24      25     NULL    NULL     
2221        Doc1        1153    31      32      NULL    28      30
2221        Doc2        1253    NULL    NULL    NULL    40      41  
2222        Doc3        1053    03      06      09      12      15

我需要将具有最新值的记录1,2,3合并到一行中，其格式将是这样。

NameID       Value1   Value2  Value3  Value4  Value5
------       ------   ------  ------  ------  ------
2221         31       32      25      40      41    
2222         03       06      09      12      15

它将使用时间戳作为参考来决定更新哪些值以及将保留哪些值。 任何帮助或开始对我来说都是不胜感激的，继续我的工作！

Answer 1

这很棘手。

在不了解pivot查询本身的情况下，也许最简单的方法是关联子查询或apply ：

select nameId,
       (select top (1) t2.documentname
        from t t2
        where t2.nameId = t.nameId and t2.documentname is not null
        order by t2.time desc
       ) as documentname,
       max(time) as time,
       (select top (1) t2.value1
        from t t2
        where t2.nameId = t.nameId and t2.value1 is not null
        order by t2.time desc
       ) as value1,
       (select top (1) t2.value2
        from t t2
        where t2.nameId = t.nameId and t2.value2 is not null
        order by t2.time desc
       ) as value2,
       . . .
from t;

Answer 2

我在这里看不到这个问题和您的问题有什么区别...

如何在SQL Server中将数据行转置为具有不同列的单行

我给您的答案是在进行数据透视之前已经取了最后一个值，如果这是一个新要求，您可能只需要调整分区即可。

无论如何，如果不可能，并且假设您也为此要求使用SQL Server 2014，则可以在当前方法上使用LAST_VALUE

WITH YourPivot AS (
    <Put your current pivot code here>
)
SELECT DISTINCT 
    NameID
    ,LAST_VALUE(Value1) OVER (PARTITION BY NameID ORDER BY CASE WHEN Value1 IS NOT NULL THEN 1 ELSE 0 END, [Time] ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) Value1
    ,LAST_VALUE(Value2) OVER (PARTITION BY NameID ORDER BY CASE WHEN Value2 IS NOT NULL THEN 1 ELSE 0 END, [Time]  ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) Value2
    ,LAST_VALUE(Value3) OVER (PARTITION BY NameID ORDER BY CASE WHEN Value3 IS NOT NULL THEN 1 ELSE 0 END, [Time]  ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) Value3
    ,LAST_VALUE(Value4) OVER (PARTITION BY NameID ORDER BY CASE WHEN Value4 IS NOT NULL THEN 1 ELSE 0 END, [Time]  ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) Value4
    ,LAST_VALUE(Value5) OVER (PARTITION BY NameID ORDER BY CASE WHEN Value5 IS NOT NULL THEN 1 ELSE 0 END, [Time]  ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING) Value5
FROM YourPivot