--1、借助newid()go--创建视图(因为在函数中无法直接使用newid())create view vnewidasselect newid() N'MacoId';go--创建函数create function getrandstr(@n int)returns varchar(max)asbegin    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 @kend --测试示例select dbo.getrandstr(75)--运行结果/*D185504AD09C4D5796F7016983E67414CEE25162EA9F43D195D43328A4CF01AC7C586521D8E*/ --我们可以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)asbegin       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_oneend--测试用例select [dbo].[m_rand](75)--运行结果/*5nN0w4o4VOkjacB5so2uvCuw2ZRrnBhxEi4IcsEOHzBbStKmR1p8ASH4N4XaxhDoDEtkX8bZ0CR*/