SQL>
SQL> CREATE TABLE employee (
2 id number,
3 name varchar(100),
4 birth_date date,
5 gender varchar2(30) );
Table created.
SQL>
SQL> INSERT INTO employee (id,name,birth_date,gender ) SELECT 300,'H',NULL,'MALE' from dual d
2 where not exists (SELECT 1 FROM employee x WHERE x.id = '300' );
1 row created.
SQL>
SQL> select * from employee;
ID
------
NAME
----------------------------------------------------------------------
BIRTH_DATE GENDER
---------- ------------------------------
300
H
null MALE
1 row selected.
SQL>
SQL> drop table employee;
Table dropped.