NULL Date field is populated with SYSDATE by default - sql

Question

I am running a query on clocking data for my company. I have a query with 2 fields: CLOCK_IN1 and CLOCK_OUT1. When I run the query I see the proper CLOCK_IN1 but the CLOCK_OUT1 is being populated with a date near SYSDATE. CLOCK_OUT1 is NULL in the database and it's replacing the NULL with this date.
Is there a setting that populates a date when it's NULL?

Answer 1

There's either
a DEFAULT value applied to that column, or
a database trigger that does it.
This is how the first works:
SQL> create table test
2 (clock_in1 date,
3 clock_out1 date default sysdate
4 );
Table created.
SQL> insert into test (clock_in1) values (date '2020-08-23');
1 row created.
SQL> alter session set nls_date_format = 'dd.mm.yyyy hh24:mi:ss';
Session altered.
SQL> select sysdate from dual;
SYSDATE
-------------------
03.11.2020 20:23:03
SQL> select * from test;
CLOCK_IN1 CLOCK_OUT1
------------------- -------------------
23.08.2020 00:00:00 03.11.2020 20:22:48
SQL>
And this is the second:
SQL> drop table test;
Table dropped.
SQL> create table test
2 (clock_in1 date,
3 clock_out1 date
4 );
Table created.
SQL> create or replace trigger trg_bi_test
2 before insert on test
3 for each row
4 begin
5 :new.clock_out1 := nvl(:new.clock_out1, sysdate);
6 end;
7 /
Trigger created.
SQL> insert into test (clock_in1) values (date '2020-08-23');
1 row created.
SQL> select * from test;
CLOCK_IN1 CLOCK_OUT1
------------------- -------------------
23.08.2020 00:00:00 03.11.2020 20:24:23
SQL>
How to "fix" it?
SQL> alter table test modify clock_out1 default null;
Table altered.
SQL>
As of the trigger, well ... it depends on what it is doing, but - removing a line that sets column value would do.