Concat內部總結給出錯誤信息

Question

我在做一個查詢，我在分區內使用行號，我想用CONCAT來組合幾個字段來構造一個全名。當我只是將這些字段添加到+它是一切正常。當我嘗試使用CONCAT功能時 - 我收到一條錯誤消息。我不明白爲什麼 - 有人可以告訴我這是不是允許在一個聚合內？

這裏是一個正常工作的代碼：

USE [AdventureWorks2012] 
SELECT 
    count([BusinessEntityID])as NumPeople 
    ,[PersonType] 
    ,max(case when rnum = 1 then [BusinessEntityID] end) as '1st ID' 
    ,max(case when rnum = 2 then [BusinessEntityID] end) as '2nd ID' 
    ,max(case when rnum = 1 then [FirstName]+' '+[LastName] end) as '1st FullName' 
    ,max(case when rnum = 2 then [FirstName]+' '+[LastName] end) as '2nd FullName' 

from 
    ( 
     Select *, row_number() over (partition by [PersonType] order by [BusinessEntityID]) as rnum 
     FROM 
     [Person].[Person] 
    ) x 
group by [PersonType] 

，它的輸出：

+-----------+------------+--------+--------+----------------+------------------+ 
| NumPeople | PersonType | 1st ID | 2nd ID | 1st FullName | 2nd FullName  | 
+-----------+------------+--------+--------+----------------+------------------+ 
| 273  | EM   | 1  | 2  | Ken Sánchez | Terri Duffy  | 
| 289  | GC   | 2091 | 2092 | David Ortiz | Qiang Wang  | 
| 18484  | IN   | 1699 | 1700 | David Robinett | Rebecca Robinson | 
| 753  | SC   | 291 | 293 | Gustavo Achong | Catherine Abel | 
| 17  | SP   | 274 | 275 | Stephen Jiang | Michael Blythe | 
| 156  | VC   | 1491 | 1493 | Paula Moberly | Suchitra Mohan | 
+-----------+------------+--------+--------+----------------+------------------+ 

這是給出了一個錯誤代碼：

USE [AdventureWorks2012] 
SELECT 
    count([BusinessEntityID])as NumPeople 
    ,[PersonType] 
    ,max(case when rnum = 1 then [BusinessEntityID] end) as '1st ID' 
    ,max(case when rnum = 2 then [BusinessEntityID] end) as '2nd ID' 
    ,max(case when rnum = 1 then (concat(p.[FirstName], stuff(p.[MiddleName],1,0,' '), stuff(p.[LastName],1,0,' ') end) as '1st FullName' 
    ,max(case when rnum = 2 then (concat(p.[FirstName], stuff(p.[MiddleName],1,0,' '), stuff(p.[LastName],1,0,' ')end) as '2nd FullName' 
from 
    ( 
     Select *, row_number() over (partition by [PersonType] order by [BusinessEntityID]) as rnum 
     FROM 
     [Person].[Person] 
    ) x 
group by [PersonType] 

這裏是錯誤：

Msg 156, Level 15, State 1, Line 9 
Incorrect syntax near the keyword 'end'. 
Msg 102, Level 15, State 1, Line 17 
Incorrect syntax near 'x'. 

我確定這只是Microsoft SQL Server不允許的東西 - 但我想知道它是什麼，無法完成 - 所以我可以確保在需要時避免這種情況。或者如果有某種方法可以做到這一點，那麼這將是偉大的...

Answer 1

我相信括號是唯一的問題在這裏。使用concat的兩條線是這樣的，如...) end) as '...，當它們應該像這樣讀取...))) end) as '...時。完整查詢如下。

USE [AdventureWorks2012] 
SELECT 
    count([BusinessEntityID])as NumPeople 
    ,[PersonType] 
    ,max(case when rnum = 1 then [BusinessEntityID] end) as '1st ID' 
    ,max(case when rnum = 2 then [BusinessEntityID] end) as '2nd ID' 
    ,max(case when rnum = 1 then (concat(p.[FirstName], stuff(p.[MiddleName],1,0,' '), stuff(p.[LastName],1,0,' '))) end) as '1st FullName' 
    ,max(case when rnum = 2 then (concat(p.[FirstName], stuff(p.[MiddleName],1,0,' '), stuff(p.[LastName],1,0,' '))) end) as '2nd FullName' 
from 
    ( 
     Select *, row_number() over (partition by [PersonType] order by [BusinessEntityID]) as rnum 
     FROM 
     [Person].[Person] 
    ) x 
group by [PersonType]