SQL Server 2008: concatenate fractions of n-rows together

Question

my table looks like:

column 1 | column 2
--------------------
   A         L
   B         M
   C         N
   D         O
   E         P
   F         Q
   G         R
   H         S
   I         T
   J         U
   K         V

Now I want to "concatenate" fractions of n-rows (n is variable) together.

For example:

-) if n = 4, the output should be:

column 1 | column 2 | column 1 | column 2 | column 1 | column 2
   A          L          E          P          I          T
   B          M          F          Q          J          U
   C          N          G          R          K          V
   D          O          H          S

-) if n = 10, the output should be:

column 1 | column 2 | column 1 | column 2
   A          L          K          V
   B          M
   C          N
   D          O
   E          P
   F          Q
   G          R
   H          S
   I          T
   J          U

I thought about using a temp table and a loop. After every iteration, I select fractions of n-rows and concatenate them together (with union). However, I think this solution could be a little slow for large datasets.

Maybe someone of you knows a better approach?

I would really appreciate if someone could help me with this.

Kind Regards

Bernhard

Answer 1

this is not complete

pivot is left,i was thinking of doing something like this,

Declare @n int=4
Declare @j int
Declare @k int
Select  @j=count(*) from #t
if(@j%@n=0)
set @k= (@j/@n)
else
set @k= (@j/@n)+1
--select @k
;with CTE as
( 
select *,ntile(@k)over(order by column1)rn from #t
)
select * from cte