SQL生成n位随机字符串

--1、随着newid()  
go  
--创建一个视图(因为不能在功能直接用于newid())  
create view vnewid  
as  
select newid() N'MacoId';  
go  
--创建函数 
create function getrandstr(@n int)  
returns varchar(max)  
as  
begin  
    declare @i int  
    set @i=ceiling(@n/32.00)  
    declare @j int  
    set @j=0  
    declare @k varchar(max)  
    set @k=''  
    while @j<@i  
    begin  
    select @k=@k+replace(cast(MacoId as varchar(36)),'-','') from vnewid  
    set @j=@j+1  
    end  
    set @k=substring(@k,1,@n)  
return @k  
end  
   
--測试演示样例 
select dbo.getrandstr(75)  
--执行结果 
/*  
D185504AD09C4D5796F7016983E67414CEE25162EA9F43D195D43328A4CF01AC7C586521D8E  
*/  
   
--我们能够发现结果中的字母都是大写的。或是都是小写的。
 
--换种方法来写下： 
go  
--创建函数 
create function [dbo].[m_rand](@mycount int)  
returns nvarchar(2000)  
as  
begin  
       declare @maco_wang table (id varchar(1))  
       declare @maco_number int,@number int;  
       declare @my_one nvarchar(max),@my_two nvarchar(max)  
       set @my_one='';set @maco_number=0; set @number =48;  
       while (@number>=48 and @number<=57) or (@number>=65 and @number<=90) or (@number>=97 and @number<=122)   
       begin  
           insert into @maco_wang select char(@number)  
           set @number=@number+1;  
           if(@number=58)  
           begin  
              set @number=65            
           end  
           if(@number=91)  
           begin       
              set @number=97     
           end  
       end  
       while @maco_number<@mycount  
       begin  
              select @my_two=id from @maco_wang  
              order by (select MacoId from dbo.m_macoview);  
              set @my_one=@my_two+@my_one;  
              set @maco_number=@maco_number+1;  
       end  
    return @my_one  
end  
--测试用例 
select [dbo].[m_rand](75)  
--的结果 
/*  
5nN0w4o4VOkjacB5so2uvCuw2ZRrnBhxEi4IcsEOHzBbStKmR1p8ASH4N4XaxhDoDEtkX8bZ0CR  
*/