求sql取字符串的首字母的函数

If Exists(Select * From sysobjects T Where T.id = object_id(N'HZ2PY') AND xtype IN(N'FN', N'IF', N'TF'))
   drop Function HZ2PY
go
Create Function HZ2PY
(
    @cString nVarChar (200)
)
Returns nVarChar(100)
AS
Begin
  Declare @nFor    Int                    --字符串循环用
  Declare @nPYFor  Int                    --拼音串循环用
  Declare @cPYString  VarChar(100)        --拼音串
  Declare @cCurChar VarChar(2)            --当前字符
  Declare @vReturn VarChar (100)                   ----将返回的结果
  Set @cPYString = '吖八嚓咑妸发旮铪讥讥咔垃呣拿讴趴七呥仨他哇哇哇夕丫匝咗'
  Set @vReturn = ''
  Set @nFor = 0
  While @nFor < Len(@cString)
    Begin
    Set @nFor = @nFor + 1
    Set @cCurChar = Substring(@cString,@nFor,1)
    Set @nPYFor = 0
    While @nPYFor < len(@cPYString)
      Begin
      Set @nPYFor = @nPYFor + 1
      If @cCurChar < Substring(@cPYString,@nPYFor,1)
        Begin
          Set @vReturn = Rtrim(@vReturn) + (Case When @nPYFor <> 1 Then Char(63 + @nPYFor) Else @cCurChar End)
          Break
        End
      Else
        Begin
          Continue
        End
      End
    End
  Return @vReturn
End


declare @tb table (id int,name varchar(20))
insert into @tb select 1,'波'
insert into @tb select 2,'病'
insert into @tb select 3,'啊'
insert into @tb select 4,'吹'
insert into @tb select 5,'崔'

select *,dbo.hz2py(name) as '首字母' from @tb

 Create  function fun_getPY 
 ( 
    @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) 

    --假如非汉字字符，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

--返回汉字首字母 

create  function [dbo].[chinese_firstletter] 
( 
  @str nvarchar(1) 
) 
returns nvarchar(1) 
as 
begin 
  declare @word nchar(1),@PY nvarchar(4000) 
  set @PY='' 

    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) 

  return @PY 
end 

go

Select dbo.chinese_firstletter('福田区第五医院')

drop function chinese_firstletter

/*

     
---- 
F

（所影响的行数为 1 行）
*/