Ahh yes I see it now. You could do this with a tally table instead of a loop. I have a view on my system that is my tally table.

create View [dbo].[cteTally] as

WITH

E1(N) AS (select 1 from (values (1),(1),(1),(1),(1),(1),(1),(1),(1),(1))dt(n)),

E2(N) AS (SELECT 1 FROM E1 a, E1 b), --10E+2 or 100 rows

E4(N) AS (SELECT 1 FROM E2 a, E2 b), --10E+4 or 10,000 rows max

cteTally(N) AS

(

SELECT ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) FROM E4

)

select N from cteTally

GO

This has millions of uses and has been referred to around here as "the swiss army knife of t-sql". You can read more about tally tables and there uses here. http://www.sqlservercentral.com/articles/T-SQL/62867/[/url]

If you are interested in using a tally table instead of a loop for this it might look something like this.

declare @n varchar(64)

DECLARE @Len int

SET @Len = 12

set @n='';

with RandomChars as

(

select top(@Len) char(n) as RandChar

from cteTally

where CHAR(n) not IN ('0', ':', ';', '`', '0', 'l', '1', '.', ',', '&', '=', '-', '(', ')', '[', ']', '?', '/', '\', '_', '''')

AND N > 32

AND N <= 122

order by NEWID()

)

select @n = @n + RandChar

from RandomChars

select @n