在T-SQL中转置数据透视

Question

我有一个包含2列单位编号和星期编号的表格，如下所示。

+--------+------------+  
| UnitID | WeekNumber |  
+--------+------------+  
|    235 |          1 |  
|    235 |          2 |  
|    235 |          3 |  
|    236 |          3 |  
|    237 |          1 |  
|    237 |          3 |  
+--------+------------+  

我需要将其转换为以下格式

+--------+-------+-------+-------+  
| UnitID | Week1 | Week2 | Week3 |  
+--------+-------+-------+-------+  
|    235 | 1     | 2     |     3 |  
|    236 | NULL  | NULL  |     3 |  
|    237 | 1     | NULL  |     3 |  
+--------+-------+-------+-------+  

但是，我得到以下结果

+--------+-------+-------+-------+  
| UnitID | Week1 | Week2 | Week3 |  
+--------+-------+-------+-------+  
|    235 |     1 | 2     | 3     |  
|    236 |     3 | NULL  | NULL  |  
|    237 |     1 | 3     | NULL  |  
+--------+-------+-------+-------+  

这是运行导致该行为的示例测试的TSQL代码。

declare @temp table
(
    UnitID int,
    WeekNumber int
)

insert into @temp(UnitID, WeekNumber) values (235, 1)
insert into @temp(UnitID, WeekNumber) values (235, 2)
insert into @temp(UnitID, WeekNumber) values (235, 3)
insert into @temp(UnitID, WeekNumber) values (236, 3)
insert into @temp(UnitID, WeekNumber) values (237, 1)
insert into @temp(UnitID, WeekNumber) values (237, 3)

select * from @temp

;With cte As
(Select UnitID, WeekNumber,
  Row_Number() Over(Partition By UnitID Order By WeekNumber asc) As rn
From @temp

)
Select UnitID, [1] As Week1, [2] As Week2, [3] As Week3
From cte
Pivot
(Max(WeekNumber) For rn In ([1], [2], [3])) As pvt;

您可以使用上面的代码填充临时表并查看结果。

Answer 1

为了获得想要的结果，我不会使用row_number()创建列标题，而只是使用当前的WeekNumber值：

;With cte As
(
  Select UnitID, WeekNumber,
    'Week'+cast(weeknumber as varchar(2)) wn
  From @temp

)
Select UnitID, [Week1], [Week2], [Week3]
From cte
Pivot
(
  Max(WeekNumber) 
  For wn In ([Week1], [Week2], [Week3])
) As pvt;

参见带有演示的SQL Fiddle