sql生成不重复的邀请码

ALTER proc [dbo].[addUser]
(
    @mid int output,@phone nvarchar(20),@regmid int,@pwd nvarchar(30),@relname nvarchar(50),
    @email nvarchar(200),@tel nvarchar(20),@sex nvarchar(2),@photo nvarchar(300),@IDNum nvarchar(20),
    @integral decimal(18,2),@flag char(1),@linkkey nvarchar(50),@qq nvarchar(30),@msn nvarchar(50),
    @disc nvarchar(500),@state char(1),@createDate datetime,@moreCol nvarchar(200),@moreCol1 nvarchar(200),
    @moreCol2 nvarchar(200)
)
as
begin
    declare @num int,@code varchar(15)
    set @code=convert(nvarchar(20),getdate(),112)+dbo.getCode(7)
    select @num=count(1) from AdminUser where [name]=@code    
    while(@num<>0)
    begin
        set @code=convert(nvarchar(20),getdate(),112)+dbo.getCode(7)
        select @num=count(1) from AdminUser where [name]=@code    
    end
    set @linkkey=@code
    insert into [hr_member]([phone],[regmid],[pwd],[relname],[email],[tel],[sex],[photo],[IDNum],[integral],
    [flag],[linkkey],[qq],[msn],[disc],[state],[createDate],[moreCol],[moreCol1],[moreCol2])values(@phone,
    @regmid,@pwd,@relname,@email,@tel,@sex,@photo,@IDNum,@integral,@flag,@linkkey,@qq,@msn,@disc,@state,
    @createDate,@moreCol,@moreCol1,@moreCol2)
    SET @mid = @@IDENTITY
end
----------------------------------------------------
create view v_random as select rand() as random
-----------------------------------------------
ALTER FUNCTION [dbo].[split](@str nvarchar(4000),@code varchar(10),@no int)  
RETURNS varchar(200)
AS  
BEGIN 
declare @intLen int
declare @count int
declare @indexb  int
declare @indexe  int
set @intLen=len(@code)
set @count=0
set @indexb=1
if @no=0
  if charindex(@code,@str,@indexb)<>0
     return left(@str,charindex(@code,@str,@indexb)-1) 
  else
     return @str
while charindex(@code,@str,@indexb)<>0
  begin
       set @count=@count+1
       if @count=@no
         break
       set @indexb=@intLen+charindex(@code,@str,@indexb)
  end 
if @count=@no
  begin

      set @indexe=@intLen+charindex(@code,@str,@indexb)
          if charindex(@code,@str,@indexe)<>0
             return substring(@str,charindex(@code,@str,@indexb)+len(@code),charindex(@code,@str,@indexe)-charindex(@code,@str,@indexb)-len(@code))
          else 
             return right(@str,len(@str)-charindex(@code,@str,@indexb)-len(@code)+1)

  end

return ''

END
------------------------------------------------------------------------
alter function getCode(@chang int)
returns varchar(50)
as
begin
    declare @sz nvarchar(69),@code varchar(50),@i int
    set @sz='0|1|2|3|4|5|6|7|8|9|a|b|c|d|e|f|j|h|i|k|l|m|n|o|p|q|r|s|t|u|v|w|x|y|z'
    set @i=0
    set @code=''
    while(@i<=@chang)
    begin
        declare @random float
        select @random=random from v_random
        set @code=@code+dbo.split(@sz,'|',ceiling(@random*35))
        set @i=@i+1
    end
    return @code
end