How to calculate the difference between two dates?

Question

Hello,
I would like to write some code which figures out how many days are between the Date_of_change (which is of datatype DATE, length 7 and of format DD-MON-YY) and the current date today. Then if the difference between Date_of_change and the current date is greater that 30 days for example then I would like to delete that record from the database.
Thanks
Doug

Answer 1

Something like this should work:
SQL> select * from emp order by hiredate ;
     EMPNO ENAME      JOB              MGR HIREDATE           SAL       COMM     DEPTNO
      7934 MILLER     CLERK           7782 21-OCT-2005       1300                    10
      7902 FORD       ANALYST         7566 22-OCT-2005       3000                    20
      7900 JAMES      CLERK           7698 23-OCT-2005        950                    30
      7876 ADAMS      CLERK           7788 24-OCT-2005       1100                    20
      7844 TURNER     SALESMAN        7698 25-OCT-2005       1500          0         30
      7839 KING       PRESIDENT            26-OCT-2005       5000                    10
      7788 SCOTT      ANALYST         7566 27-OCT-2005       3000                    20
      7782 CLARK      MANAGER         7839 28-OCT-2005       2450                    10
      7698 BLAKE      MANAGER         7839 29-OCT-2005       2850                    30
      7654 MARTIN     SALESMAN        7698 30-OCT-2005       1250       1400         30
      7566 JONES      MANAGER         7839 31-OCT-2005       2975                    20
      7521 WARD       SALESMAN        7698 01-NOV-2005       1250        500         30
      7499 ALLEN      SALESMAN        7698 02-NOV-2005       1600        300         30
      7369 SMITH      CLERK           7902 03-NOV-2005        800                    20
14 rows selected.
SQL> delete from emp where hiredate < sysdate - 30 ;
10 rows deleted.
SQL> select * from emp order by hiredate ;
     EMPNO ENAME      JOB              MGR HIREDATE           SAL       COMM     DEPTNO
      7566 JONES      MANAGER         7839 31-OCT-2005       2975                    20
      7521 WARD       SALESMAN        7698 01-NOV-2005       1250        500         30
      7499 ALLEN      SALESMAN        7698 02-NOV-2005       1600        300         30
      7369 SMITH      CLERK           7902 03-NOV-2005        800                    20
4 rows selected.
SQL>