SQL: Structured Query Language - Oracle 10g Database Administration Concepts and Implementation Made Simple - page 46

Example:
UPDATE emp
SET comm = NULL
WHERE job = 'TRAINEE';
Example:
INSERT INTO dept
VALUES (50, 'PRODUCTION', 'SAN FRANCISCO');
Another version,
INSERT INTO emp (empno, ename, job, sal, comm,
deptno)
VALUES (7890, 'JINKS', 'CLERK', 1.2E3, NULL, 40);
Example:
DELETE FROM emp
WHERE JOB = 'SALESMAN' AND COMM < 100;