Subtract one date from another, yielding the number of days between the two dates. : Date Arithmetic « Date Timestamp Functions « Oracle PL/SQL Tutorial

1. Oracle PL/SQL Tutorial
2. Date Timestamp Functions
3. Date Arithmetic

The following example subtracts July 31, 2003, from August 2, 2003:

SQL> SELECT TO_DATE('02-AUG-2003') - TO_DATE('31-JUL-2003') FROM dual;

TO_DATE('02-AUG-2003')-TO_DATE('31-JUL-2003')
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                                            2

SQL>