PL/SQL How to get X day ago from a Date as Date?

Question

I want to get 100 days ago from 08-APR-13, as date.

How to do it with pl/sql?

Answer 1

Assumption was made that the 08-APR-13 is a string in your situation. So you need convert it to date using to_date function, and then simply subtract 100 literal.

• 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
  

OR

     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