IF OBJECT_ID('dbo.vGUID') IS NOT NULL drop view dbo.vGUID
GO
create view dbo.vGUID
as
	select newid() as r;
GO
IF OBJECT_ID('dbo.RandString') IS NOT NULL drop function dbo.RandString
GO
create function dbo.RandString (@x int,@y int)
returns varchar(100)
as
begin
return(SELECT ''+ CHAR(c.NC)  FROM 
(select top 1 number  as N from master..spt_values 
 cross apply dbo.vGUID g
 where type = 'p'  and number between @x  AND @y 
 ORDER BY ROW_NUMBER()OVER(ORDER BY g.R)) N
join 
(select number  as NC, ROW_NUMBER()OVER(ORDER BY g.R)  AS N
from master..spt_values 
 cross apply dbo.vGUID g
where type = 'p'  and ((number between 65  AND 90) OR (number between 97  AND 122)))C
ON C.N <= N.N
FOR XML PATH('')) 
end
GO

declare @Mytable table  (id int)
insert into @Mytable(id) values(1),(2),(3),(4),(5)
declare @x int =5 ,  @y int =10

SELECT t.id,dbo.RandString(@x,@y)
FROM @Mytable t