为什么to_char（0，'B9999'）的例外是0？

Question

What makes the number 0 an exception to Oracle to_char(number,'B9999') mask? In this query 0 doesn't print at all.

How can I left pad all my numbers including 0 with spaces? Is lpad() the only alternative?

select to_char(0,'B09999') as num_fmt from dual union all
select to_char(0,'B9999') as num_fmt from dual  union all
select to_char(300,'B9999') as num_fmt from dual  union all
select to_char(-300,'B9999') as num_fmt from dual ;

Answer 1

You can use to_char(yourVal,'999') format model to get left padded blanks for integers of three digits ( Leading zeros are blank, except for a zero value ).

If you need more, than raise the number of nines upto number of digits within your integer values :

select to_char(0,'999') as num_fmt from dual union all
select to_char('00','999')         from dual union all
select to_char('016','999')        from dual union all
select to_char(17,'999')           from dual union all
select to_char(314,'999')          from dual union all
select to_char(-314,'999')         from dual;

NUM_FMT
-------
      0
      0
     16
     17
    314
   -314

Demo