是否可以在sql中使用字母数字序列生成器

Question

我需要编写一个SQL查询来在SQL中打印以下的aphanumberic序列

0001,0002,...,0009,000A,...,000Z,...,0010,0011,...,001A,...等等......,ZZZZ

请注意:所有字符都是大写的.

提前致谢

Answer 1

你可以创建一个这样的函数:

create function to_base_36 (n integer) return varchar2
is
  q integer;
  r varchar2(100);
begin
  q := n;
  while q >= 36 loop
     r := chr(mod(q,36)+case when mod(q,36) < 10 then 48 else 55 end) || r;
     q := floor(q/36);
  end loop;
  r := chr(mod(q,36)+case when mod(q,36) < 10 then 48 else 55 end) || r;
  return lpad(r,4,'0');
end;

然后像这样使用它:

select rownum, to_base_36(rownum)
from dual
connect by level < 36*36*36*36;

或者,不创建功能:

with digits as
( select n, chr(mod(n,36)+case when mod(n,36) < 10 then 48 else 55 end) d
  from (Select rownum-1 as n from dual connect by level < 37)
)
select d1.n*36*36*36 + d2.n*36*36 + d3.n*36 + d4.n, d1.d||d2.d||d3.d||d4.d
from digits d1, digits d2, digits d3, digits d4