sql uniqueidentifier转varchar

--- 
DECLARE @myid uniqueidentifier
SET @myid = NEWID()
SELECT CONVERT(char(255), @myid) AS 'char';
GO
-- 
declare @allstring char(255),@AreaUid Uniqueidentifier
set @AreaUid='37A1DA94-4AC6-4ED0-B96F-BA3FE6AEACC8'
set @allstring= cast(@AreaUid as char(255))
select @allstring
-- 
declare @allstring char(255),@AreaUid Uniqueidentifier,@s varchar(200)
set @AreaUid='37A1DA94-4AC6-4ED0-B96F-BA3FE6AEACC8'
set @allstring= CONVERT(char(255),@AreaUid)
set @s=cast(@allstring as varchar(200))
select @allstring,@s
-- 
declare @allstring char(255),@AreaUid Uniqueidentifier,@s varchar(200)
set @AreaUid='37A1DA94-4AC6-4ED0-B96F-BA3FE6AEACC8'
select @s=CONVERT(varchar(200),cast(@AreaUid as char(225)))
select @s