SQL> create table t ( t1 interval day to second);

Table created.

SQL> insert into t values ( systimestamp - cast(systimestamp-2.34 as timestamp) );

1 row created.

SQL>
SQL> select t1 from t;

T1
---------------------------------------------------------------------------
+02 08:09:36.575000

SQL> select to_char(t1) from t;

TO_CHAR(T1)
--------------------
+02 08:09:36.575000

SQL> insert into t values ( to_dsinterval('+02 08:09:36.374000'));

1 row created.

SQL> select
  2    extract(day from t1) d,
  3    extract(hour from t1) h,
  4    extract(minute from t1) m,
  5    extract(second from t1) s
  6  from t;

         D          H          M          S
---------- ---------- ---------- ----------
         2          8          9     36.575
         2          8          9     36.374