Question

我有一个看起来像这样的表：

CreatedDate                  TargetDate               Value        Name     rowNum
2016-10-06 16:30:00.000 2016-10-16 00:00:00.000     17.97566      Joseph      1
2016-10-06 16:20:00.000 2016-10-16 00:00:00.000     1.176129      Heidi       1
2016-10-06 16:20:00.000 2016-10-15 23:00:00.000     1.196976      Heidi       1
2016-10-06 16:30:00.000 2016-10-15 23:00:00.000     15.15687      Joseph      1
2016-10-06 16:30:00.000 2016-10-15 22:00:00.000     11.04526      Joseph      1
2016-10-06 16:20:00.000 2016-10-15 22:00:00.000     1.539218      Heidi       1

我想把它转移到这样的表格中：

gen_dt_Joseph           gen_dt_Heidi            TargetDate              JosephValue     HeidiValue
2016-10-06 16:30:00.000 2016-10-06 16:20:00.000 2016-10-16 00:00:00.000 17.9757         1.1761
2016-10-06 16:30:00.000 2016-10-06 16:20:00.000 2016-10-15 23:00:00.000 15.1569         1.1970
2016-10-06 16:30:00.000 2016-10-06 16:20:00.000 2016-10-15 22:00:00.000 11.0453         1.5392

我的查询如下：

select CreatedDate as gen_dt_Joseph 
  ,CreatedDate as gen_dt_Heidi
  ,TargetDate  [TargetDate]
  ,[Joseph]   [JosephValue]
  ,[Heidi] [HeidiValue]
 FROM theTable
 pivot (max(value) for Name in ( [Joseph],[Heidi])
 ) as pvt
order by TargetDate DESC

当然这是回归：

gen_dt_Joseph           gen_dt_Heidi            TargetDate              JosephValue     HeidiValue
2016-10-06 16:30:00.000 2016-10-06 16:30:00.000 2016-10-16 00:00:00.000 17.9757         NULL
2016-10-06 16:20:00.000 2016-10-06 16:20:00.000 2016-10-16 00:00:00.000 NULL         1.1761
2016-10-06 16:30:00.000 2016-10-06 16:30:00.000 2016-10-15 23:00:00.000 15.1569         NULL
2016-10-06 16:20:00.000 2016-10-06 16:20:00.000 2016-10-15 23:00:00.000 NULL         1.1970
2016-10-06 16:30:00.000 2016-10-06 16:30:00.000 2016-10-15 22:00:00.000 11.0453         NULL
2016-10-06 16:20:00.000 2016-10-06 16:20:00.000 2016-10-15 22:00:00.000 NULL         1.5392

所以基本上我想要一个记录包含每个TargetDate的两个值，但如果我有两个不同的CreatedDate，我想记录每个记录的最新记录。谁能帮我走最后一步呢？

Answer 1

当必须转动多个列时，我更喜欢简单地使用CASE WHEN语句和标准GROUP BY子句。以下查询将为您提供所需的结果。

SELECT      MAX(
                CASE Name 
                    WHEN    'Joseph' THEN CreatedDate
                    ELSE    NULL
                END
            ) AS gen_dt_Joseph
            ,MAX(
                CASE Name 
                    WHEN    'Heidi' THEN CreatedDate
                    ELSE    NULL
                END
            ) AS gen_dt_Heidi
            ,TargetDate
            ,MAX(
                CASE Name 
                    WHEN    'Joseph' THEN Value
                    ELSE    NULL
                END
            ) AS JosephValue
            ,MAX(
                CASE Name 
                    WHEN    'Heidi' THEN Value
                    ELSE    NULL
                END
            ) AS HeidiValue
FROM        theTable
GROUP BY    TargetDate
ORDER BY    TargetDate DESC

如何根据日期将两行转换为一行

1 个答案: