Just to toss my hat in the ring...

create procedure dbo.usp_permutate

@charset nvarchar(256) = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'

as

set nocount on

-- a set of all values in the charset

create table #set ( k int, v nchar(1) )

declare @i int, @C nvarchar(5)

declare @select nvarchar(4000)

declare @from nvarchar(4000)

select

@i = 1

, @select = 's1.v '

, @from = '#set s1 '

insert into #set ( k, v ) values ( 1, substring(@charset, @i, 1) )

while @i < len(@charset) begin

set @i = @i + 1

set @C = convert(nvarchar(5), @i)

insert into #set ( k, v ) values ( 1, substring(@charset, @i, 1) )

set @select = @select + '+ s' + @C + '.v '

set @from = @from + 'join #set s' + @C + ' on s' + @C + '.k = s1.k '

end

-- output query

exec( 'select ' + @select + 'as permutation from ' + @from + 'order by permutation' )

-- clean up

drop table #set