SQL Server查詢側重於“透視”包含非數字數據的表

Question

表名稱：職業

**Name  Occupation**  
Samantha    Doctor    
Julia   Actor
Maria   Actor
Meera   Singer
Ashely  Professor
Ketty   Professor
Christeen   Professor
Jane    Actor
Jenny   Doctor
Priya   Singer

---

目標是編寫一個查詢，該查詢將“透視”上述表數據，以便顯示以下結果：

Jenny    Ashley     Meera  Jane
Samantha Christeen  Priya  Julia
NULL     Ketty      NULL   Maria

我寫了以下查詢：

 WITH pivot_data AS
(
SELECT Occupation as Occupation1,  -- Grouping Column
Occupation, -- Spreading Column
Name -- Aggregate Column
FROM Occupations
)
SELECT  [Doctor], [Professor], [Singer], [Actor]
FROM pivot_data 
PIVOT (max(Name) 
       FOR Occupation IN ([Doctor], [Professor], [Singer], [Actor])
                                                            ) AS p;

不幸的是，上述查詢給出了以下錯誤結果：

Doctor  Professor   Singer  Actor    
NULL    NULL    NULL    Maria    
Samantha    NULL    NULL    NULL    
NULL    Ketty   NULL    NULL    
NULL    NULL    Priya   NULL

有人可以發布將顯示所需結果的sql查詢嗎？（此外，如果您可以使用sql server“ pivot”命令執行一個查詢，而使用sql server“ pivot”命令執行另一個查詢，這將非常有幫助）

Answer 1

我不會為此使用數據透視。 條件聚合更容易編寫和理解。 它的性能幾乎總是略勝一籌。

首先，我必須將這些數據轉換為可消耗的東西。 這是您將來應該發布此類信息的方式。

declare @Something table
(
    Name varchar(20)
    , Occupation varchar(20)
)

insert @Something values
('Samantha', 'Doctor')
, ('Julia', 'Actor')
, ('Maria', 'Actor')
, ('Meera', 'Singer')
, ('Ashely', 'Professor')
, ('Ketty', 'Professor')
, ('Christeen', 'Professor')
, ('Jane', 'Actor')
, ('Jenny', 'Doctor')
, ('Priya', 'Singer')
;

現在，我們可以使用這些數據輕松地生成您的輸出。

with NumberedRows as
(
    select * 
        , RowNum = ROW_NUMBER() over(partition by Occupation order by name)
    from @Something
)

select Doctor = max(case when nr.Occupation = 'Doctor' then nr.Name end)
    , Professor = max(case when nr.Occupation = 'Professor' then nr.Name end)
    , Singer = max(case when nr.Occupation = 'Singer' then nr.Name end)
    , Actor = max(case when nr.Occupation = 'Actor' then nr.Name end)
from NumberedRows nr
group by nr.RowNum