SQL Pivot函数获取top notes字段

Question

请查看此问题以获得更多背景信息:question 1我使用下面的代码使用数据透视函数创建了一个信息列表

  WITH List AS
    (
        SELECT 'x' AS Company, 'Call'    AS ContactType, '01/01/2016' AS StartTime UNION ALL
        SELECT 'x' AS Company, 'Call'    AS ContactType, '02/01/2016' AS StartTime UNION ALL
        SELECT 'x' AS Company, 'Meeting' AS ContactType, '02/01/2016' AS StartTime UNION ALL
        SELECT 'x' AS Company, 'Email'   AS ContactType, '03/01/2016' AS StartTime UNION ALL
        SELECT 'y' AS Company, 'Meeting' AS ContactType, '01/01/2016' AS StartTime UNION ALL
        SELECT 'y' AS Company, 'Email'   AS ContactType, '01/02/2016' AS StartTime UNION ALL
        SELECT 'y' AS Company, 'Call'    AS ContactType, '02/02/2016' AS StartTime UNION ALL
        SELECT 'z' AS Company, 'Call'    AS ContactType, '09/01/2016' AS StartTime UNION ALL
        SELECT 'z' AS Company, 'Call'    AS ContactType, '24/01/2016' AS StartTime UNION ALL
        SELECT 'z' AS Company, 'Meeting' AS ContactType, '10/01/2016' AS StartTime UNION ALL
        SELECT 'z' AS Company, 'Meeting' AS ContactType, '06/01/2016' AS StartTime 
    )


    SELECT Company, Call, Meeting, Email
    FROM
    (
      SELECT StartTime, ContactType, Company
        FROM List
    ) L
    PIVOT
    (
      MAX(StartTime)
      FOR ContactType IN (Call, Meeting, Email)
    ) CT

这有助于生成表格结果:

+---------+------------+------------+------------+
| Company |    Call    |  Meeting   |   Email    |
+---------+------------+------------+------------+
| x       | 02/01/2016 | 02/01/2016 | 03/01/2016 |
| y       | 02/02/2016 | 01/01/2016 | 01/02/2016 |
| z       | 24/01/2016 | 10/01/2016 | Null       |
+---------+------------+------------+------------+

我想通过将一个附加列合并到我的原始查询中来更进一步。我想像这样在查询中添加注释:

WITH List AS
    (
        SELECT 'x' AS Company, 'Call'    AS ContactType, '01/01/2016' AS StartTime, 'blablabla1' as Note UNION ALL
        SELECT 'x' AS Company, 'Call'    AS ContactType, '02/01/2016' AS StartTime, 'blablabla2' as Note UNION ALL
        SELECT 'x' AS Company, 'Meeting' AS ContactType, '02/01/2016' AS StartTime, 'blablabla3' as Note UNION ALL
        SELECT 'x' AS Company, 'Email'   AS ContactType, '03/01/2016' AS StartTime, 'blablabla4' as Note UNION ALL
        SELECT 'y' AS Company, 'Meeting' AS ContactType, '01/01/2016' AS StartTime, 'blablabla5' as Note UNION ALL
        SELECT 'y' AS Company, 'Email'   AS ContactType, '01/02/2016' AS StartTime, 'blablabla6' as Note UNION ALL
        SELECT 'y' AS Company, 'Call'    AS ContactType, '02/02/2016' AS StartTime, 'blablabla7' as Note UNION ALL
        SELECT 'z' AS Company, 'Call'    AS ContactType, '09/01/2016' AS StartTime, 'blablabla8' as Note UNION ALL
        SELECT 'z' AS Company, 'Call'    AS ContactType, '24/01/2016' AS StartTime, 'blablabla9' as Note UNION ALL
        SELECT 'z' AS Company, 'Meeting' AS ContactType, '10/01/2016' AS StartTime, 'blablabla10' as Note UNION ALL
        SELECT 'z' AS Company, 'Meeting' AS ContactType, '06/01/2016' AS StartTime, 'blablabla11' as Note 
    )

我想生成的表输出是:

+---------+------------+------------+------------+------------+
| Company |    Call    |  Meeting   |   Email    |    Note    |
+---------+------------+------------+------------+------------+
| x       | 02/01/2016 | 02/01/2016 | 03/01/2016 | blablabla4 |
| y       | 02/02/2016 | 01/01/2016 | 01/02/2016 | blablabla7 |
| z       | 24/01/2016 | 10/01/2016 | Null       | blablabla9 |
+---------+------------+------------+------------+------------+

现在是棘手的一点。我希望根据联系方式选择的笔记是最新的笔记。在第一行注释中:blablabla4 被选中，因为最近的联系是通过电子邮件“03/01/2016”进行的，因此它选择了这条注释。

有没有人知道我如何在不使用子查询我自己的数据的情况下实现这一目标。

Answer 1

您可以使用 ROW_NUMBER() 获取最新的笔记

WITH List AS
    (
        SELECT 'x' AS Company, 'Call'    AS ContactType, '01/01/2016' AS StartTime, 'blablabla1' as Note UNION ALL
        SELECT 'x' AS Company, 'Call'    AS ContactType, '02/01/2016' AS StartTime, 'blablabla2' as Note UNION ALL
        SELECT 'x' AS Company, 'Meeting' AS ContactType, '02/01/2016' AS StartTime, 'blablabla3' as Note UNION ALL
        SELECT 'x' AS Company, 'Email'   AS ContactType, '03/01/2016' AS StartTime, 'blablabla4' as Note UNION ALL
        SELECT 'y' AS Company, 'Meeting' AS ContactType, '01/01/2016' AS StartTime, 'blablabla5' as Note UNION ALL
        SELECT 'y' AS Company, 'Email'   AS ContactType, '01/02/2016' AS StartTime, 'blablabla6' as Note UNION ALL
        SELECT 'y' AS Company, 'Call'    AS ContactType, '02/02/2016' AS StartTime, 'blablabla7' as Note UNION ALL
        SELECT 'z' AS Company, 'Call'    AS ContactType, '09/01/2016' AS StartTime, 'blablabla8' as Note UNION ALL
        SELECT 'z' AS Company, 'Call'    AS ContactType, '24/01/2016' AS StartTime, 'blablabla9' as Note UNION ALL
        SELECT 'z' AS Company, 'Meeting' AS ContactType, '10/01/2016' AS StartTime, 'blablabla10' as Note UNION ALL
        SELECT 'z' AS Company, 'Meeting' AS ContactType, '06/01/2016' AS StartTime, 'blablabla11' as Note 
    )
Select Company
      ,Call    = max(case when ContactType='Call'    then StartTime end)
      ,Meeting = max(case when ContactType='Meeting' then StartTime end)
      ,Email   = max(case when ContactType='Email'   then StartTime end)
      ,Note    = max(case when ContactType<>'Email' and RN=1 then Note end)
 From (
        Select *
              ,RN = Row_Number() over (Partition By Company,case when ContactType <>'EMail' then 1 else 0 end Order By StartTime Desc) 
         from List
      ) A
 Group BY Company

返回

Company Call        Meeting     Email       Note
x       02/01/2016  02/01/2016  03/01/2016  blablabla3
y       02/02/2016  01/01/2016  01/02/2016  blablabla7
z       24/01/2016  10/01/2016  NULL        blablabla9