CREATE TABLE employees (employee_id NUMBER, first_name CLOB, last_name CLOB, email CLOB, phone_number CLOB, hire_date TIME, job_id CLOB, salary NUMBER, commission_pct NUMBER, manager_id NUMBER, department_id NUMBER)
CREATE TABLE countries (country_id CLOB, country_name CLOB, region_id NUMBER)
CREATE TABLE regions (region_id NUMBER, region_name CLOB)
CREATE TABLE locations (location_id NUMBER, street_address CLOB, postal_code CLOB, city CLOB, state_province CLOB, country_id CLOB)
CREATE TABLE job_history (employee_id NUMBER, start_date TIME, end_date TIME, job_id CLOB, department_id NUMBER)
CREATE TABLE departments (department_id NUMBER, department_name CLOB, manager_id NUMBER, location_id NUMBER)
CREATE TABLE jobs (job_id CLOB, job_title CLOB, min_salary NUMBER, max_salary NUMBER)

Return all information about employees with salaries between 8000 and 12000 for which commission is not null or where their department id is not 40.
SELECT * FROM employees WHERE salary BETWEEN 8000 AND 12000 AND commission_pct <> "null" OR department_id <> 40
SELECT * FROM "employees" WHERE ("commission_pct" <> "null" OR "department_id" <> 40) AND ("department_id" <> 40 OR "salary" <= 12000) AND ("department_id" <> 40 OR "salary" >= 8000)