Question

有人可以帮我解决这个问题吗？我需要用我的数据做两件事。

我需要获得最长日期
我需要连接Proj_Use列中的值

我的数据如下：

Report_Date  |  Program  |  Project  |  Proj_Mgr  |  Region  |  Proj_Use

6/5/2017  |  PG1  |  Prj01  |  Anne  |  East  |  PU1

6/4/2017  |  PG1  |  Prj01  |  Anne  |  East  |  PU2

6/3/2017  |  PG1  |  Prj01  |  Anne  |  East  |  PU3

6/5/2017  |  PG2  |  Prj02  |  Monica  |  West  | PU4

6/4/2017  |  PG2  |  Prj02  |  Monica  |  West  |  PU5

6/3/2017  |  PG2  |  Prj02  |  Monica  |  West  |  PU6

我的结果应如下所示：

Report_Date Program Project Proj_MgrRegion  Proj_Use

6/5/2017 | PG1 | Prj01 | Anne | East | PU1, PU2, PU3

6/5/2017 | PG2 | Prj02 | Monica | West | PU4, PU5, PU6

我可以使用以下代码获取最长日期：

    SELECT   t.[Report_Date]
        ,t.[Program]
        ,t.[Project]
        ,t.[Proj_Mgr]
        ,t.[Region]
        ,t.[Proj_Use]
    FROM project_table t
    JOIN
    (SELECT MAX([Report_Date]) as [Report Date], [Program]
        FROM project_table
        GROUP BY [Program]) max
        ON t.[Report_Date] = max.[Report Date]
        AND t.[Program] = max.[Program]

我在论坛上搜索了一种连接方法，并找到了sql server的group_concat方法。我已经尝试将其添加到代码中并提出了这个：

    SELECT   t.[Report_Date]
        ,t.[Program]
        ,t.[Project]
        ,t.[Proj_Mgr]
        ,t.[Region]
        ,STUFF ((
            SELECT ',' + t.[Proj_Use]
                FROM project_table
                FOR XML PATH ('')), 1,1, '') AS [Project Use]
    FROM project_table t
    JOIN
    (SELECT MAX([Report_Date]) as [Report Date], [Program]
        FROM project_table
        GROUP BY [Program]) max
        ON t.[Report_Date] = max.[Report Date]
        AND t.[Program] = max.[Program]

当我尝试使用我的真实数据运行时，查询运行超过20分钟而没有产生结果。

如果我正确构建了此查询，或者是否有更好的方法来获取我正在寻找的结果，有人能告诉我吗？

感谢您的帮助。

Answer 1

我期待这样的事情：

SELECT pt.*,
       STUFF((SELECT ',' + pt2.[Proj_Use]
              FROM project_table pt2
              WHERE pt2.Program = pt.Program
              ORDER BY pt2.[Report Date]
              FOR XML PATH ('')
             ), 1, 1, '') AS [Projects Used]
FROM (SELECT pt.*,
             ROW_NUMBER() OVER (PARTITION BY Program ORDER BY [Report Date] DESC) as seqnum
      FROM project_table t
     ) pt
WHERE seqnum = 1;

至少，用于连接的子查询没有与外部查询相关的子句（因此中间字符串可能非常长）。可能还有其他问题。

Answer 2

您遗失的一件大事是子查询中的where子句。

使用stuff() with select ... for xml path ('') method of string concatenation。

试试这个：

select
    ReportDate = max(t.Report_Date)
  , t.Program
  , t.Project
  , t.Proj_Mgr
  , t.Region
  , [Project_Use] = stuff((
   select ',' + i.Proj_Use
   from project_table i
   where i.Program = t.Program
     and i.Project = t.Project
     and i.Proj_Mgr = t.Proj_Mgr
     and i.Region = t.Region
   for xml path(''), type).value('.','nvarchar(max)')
   , 1, 1, '') 
from project_table t
group by t.Program, t.Project, t.Proj_Mgr, t.Region

rextester演示：http://rextester.com/SEBKZD40038

返回：

+------------+---------+---------+----------+--------+-------------+
| ReportDate | Program | Project | Proj_Mgr | Region | Project_Use |
+------------+---------+---------+----------+--------+-------------+
| 2017-06-04 | pg1     | Prj01   | Anne     | East   | pu1,pu2,pu3 |
| 2017-06-04 | pg2     | Prj02   | Monica   | West   | pu4,pu5,pu6 |
+------------+---------+---------+----------+--------+-------------+

最大日期和连接在单独的列上

2 个答案: