sql 中实现取得汉字首写字母

create function [dbo].[fn_Get_Chinese_First_Letter](@Str nvarchar(400))
returns nvarchar(4000)
as
begin
declare @strlen int,@re nvarchar(4000)
declare @t table(chr nchar(1) collate Chinese_PRC_CI_AS,letter nchar(1))
insert @t select '吖','A' union all select '八','B'
union all select '嚓','C' union all select '咑','D'
union all select '妸','E' union all select '发','F'
union all select '旮','G' union all select '铪','H'
union all select '丌','J' union all select '咔','K'
union all select '垃','L' union all select '嘸','M'
union all select '拏','N' union all select '噢','O'
union all select '妑','P' union all select '七','Q'
union all select '呥','R' union all select '仨','S'
union all select '他','T' union all select '屲','W'
union all select '夕','X' union all select '丫','Y'
union all select '帀','Z'

select @strlen=len(@str),@re=''
while @strlen>0
begin
select top 1 @re=letter+@re,@strlen=@strlen-1
from @t a where chr<=substring(@str,@strlen,1)
order by chr desc
if @@rowcount=0
select @re=substring(@str,@strlen,1)+@re,@strlen=@strlen-1
end
return(@re)
end