Oracle TO_DATE with only time input will add date component based on what logic? -

running code in oracle 11/12:

select to_date('101200', 'hh24miss') dual 

will return date component oracle automatically adds based on logic?

eg:

select to_char(to_date('101200', 'hh24miss'), 'yyyymmdd') dual 

returns

20160701 

we see added date component set first day of current month. logic come from?

thanks in advance

a value of date data type has date , time components. if specify time portion of datetime value did, date portion defaults first day of current month.

here 1 of places (7th paragraph) in oracle documentation behavior documented.

there undocumented time literal , time data type (needs enabled via 10407 (datetime time datatype creation) event) if need use , store time, without date part.

here small demonstration of using time literal , time data type. again it's undocumented , unsupported feature.

sql> select time '11:32:00' res   2    dual;  res  ------------------------   11.32.00.000000000       

you can use time literal without enabling 10407 event, in order able define column of time data type 10407 event needs enabled:

sql> create table time_table(time_col time); create table time_table(time_col time)                                  * error @ line 1: ora-00902: invalid datatype     -- enable 10407 event  sql> alter session set events '10407 trace name context forever, level 1';  session altered. 

now can create table column of time data type:

sql> create table time_table(time_col time);  table created.   sql> insert time_table(time_col)   2    values(time '11:34:00');  1 row created.  sql> select * time_table;  time_col  ---------------  11.34.00  sql> alter session set events '10407 trace name context off';  session altered.