In Oracle, SYSDATE
is a function that returns both date and time component. Difference of two DATE
datatype values returns number of days between them. Therefore, as SYSDATE
also contains hours, minutes and seconds, you'll almost always get a decimal number as the result (unless you run that piece of code at midnight).
Therefore, I presume that you'd - actually - want to truncate SYSDATE
which then "removes" time component (sets it to 00:00:00):
SQL> select SYSDATE - TO_DATE('30-12-1899','dd-mm-yyyy') from dual;
SYSDATE-TO_DATE('30-12-1899','DD-MM-YYYY')
------------------------------------------
44715.3208
SQL> select trunc(SYSDATE) - TO_DATE('30-12-1899','dd-mm-yyyy') from dual;
TRUNC(SYSDATE)-TO_DATE('30-12-1899','DD-MM-YYYY')
-------------------------------------------------
44715
SQL>
As of 0.2279: it is - as I said - number of days. To quickly demonstrate it: if you want to get number of hours, you'd multiply it by 24 (the rest by 60 to get minutes, and its rest by 60 again to get seconds):
SQL> select 0.2279 * 24 as hours from dual;
HOURS
----------`enter code here`
5.4696
SQL> select 0.4696 * 60 as minutes from dual;
MINUTES
----------
28.176
SQL> select 0.176 * 60 as seconds from dual;
SECONDS
----------
10.56
SQL>
Which means that you ran that query today at 05:28:10.