Oracle中生成包含指定位数大小写字符和数字的函数

create or replace function NewRndStr(n_num in number) return varchar2 is
        i integer default 0;
        v_token varchar2(50) default '';
    begin
        while i < n_num loop
            if mod(round(dbms_random.value(1, 2)), 2) > 0 then
                --生成字符
                if (mod(round(dbms_random.value(1, 2)), 2) > 0) then
                    --生成大写字符
                    v_token := concat(v_token,chr(65 + floor(dbms_random.value(0, 26))));
                else
                    --生成小写字符
                    v_token := concat(v_token,chr(97 + floor(dbms_random.value(0, 26))));
                end if;
            else
                --生成数字
                v_token := concat(v_token,to_char(floor(dbms_random.value(0, 10))));
            end if;
            i := i + 1;
        end loop;
        return v_token;
    end;