假设情况是08-APR-13您所处的字符串。因此，您需要将其转换为dateusingto_date函数，然后简单地减去100个文字。

• SQL

  SQL> select (to_date('08-APR-13', 'DD-MON-RR') - 100) res
  

  2 from dual
  3 /

  RES

  29-12-2012

• PL / SQL

  SQL> declare
  

  2 l_res_date date;
  3 l_in_date varchar2(11) := ‘08-APR-13’;
  4 begin
  5 select (to_date(l_in_date, ‘DD-MON-RR’) - 100)
  6 into l_res_date
  7 from dual;
  8
  9 dbms_output.put_line(to_char(l_res_date, ‘dd-mon-yy’));
  10 end;
  11 /

  29-dec-12

  PL/SQL procedure successfully completed

或者

     SQL> declare
       2    l_res_date date;
       3    l_in_date  varchar2(11) := '08-APR-13';
       4  begin
       5  
       6    l_res_date := to_date(l_in_date, 'DD-MON-RR') - 100;
       7  
       8    dbms_output.put_line(to_char(l_res_date, 'dd-mon-yy'));
       9  end;
       10  /

       29-dec-12

       PL/SQL procedure successfully completed