sql函数 获取汉字词组首字母

/********************************************************************************* 
*函数名称 : [F_GetZM]

*功能描述 : 获取汉字拼音首字母

*输入参数 : @str  ---要获取首字母的汉字词组

*返 回 值 : nvarchar(4000)
  
***********************************************************************************/

ALTER function [dbo].[F_GetZM]
(
	@str nvarchar(4000)
) 
returns nvarchar(4000) 
as 
begin 
	declare @word nchar(1),@PY nvarchar(4000) 
	set @PY='' 
	while len(@str)>0 
	begin 
		set @word=left(@str,1) 
		--如果非汉字字符，返回原字符 
		set @PY=@PY+(case when unicode(@word) between 19968 and 19968+20901 
					then (select top 1 PY from ( 
								select 'A' as PY,N'驁' as word 
								union all select 'B',N'簿' 
								union all select 'C',N'錯' 
								union all select 'D',N'鵽' 
								union all select 'E',N'樲' 
								union all select 'F',N'鰒' 
								union all select 'G',N'腂' 
								union all select 'H',N'夻' 
								union all select 'J',N'攈' 
								union all select 'K',N'穒' 
								union all select 'L',N'鱳' 
								union all select 'M',N'旀' 
								union all select 'N',N'桛' 
								union all select 'O',N'漚' 
								union all select 'P',N'曝' 
								union all select 'Q',N'囕' 
								union all select 'R',N'鶸' 
								union all select 'S',N'蜶' 
								union all select 'T',N'籜' 
								union all select 'W',N'鶩' 
								union all select 'X',N'鑂' 
								union all select 'Y',N'韻' 
								union all select 'Z',N'咗' 
								) T  
						where word>=@word collate Chinese_PRC_CS_AS_KS_WS  
						order by PY ASC) 
					else @word end) 
						set @str=right(@str,len(@str)-1) 
	end 
	return @PY 
end