Transpose Pivot in T-SQL

Question

I have a table with 2 columns Unit Number and Week Number as below.

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

I need it trasformed to the following format

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

However, I am getting the following result

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

Here is the TSQL code to run a sample test that resulted in the behavior.

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;

You can use the above code the populate a temp table and see the results.

Answer 1

To get the result that you want I wouldn't use row_number() to create your column headers, I would just use your current values of WeekNumber :

;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;

See SQL Fiddle with Demo