DECLARE @B2 VARBINARY(8000),@id nvarchar(4000),@id1 varchar(8000),@id2 nvarchar(4000)
set @id='大家好'---原来内容
SET @id1 = CAST(@id AS VARBINARY(8000))----改变后的内容
set @id2=cast(@id1 as VARBINARY(8000))---恢复到原来
select @id as original,@id1 as new,@id2 as restored