| Column | Data Type | Nullable | Default | Description |
| EMPLOYEE_ID | NUMBER(6, 0) | not null | | A not null column in the complex primary key employee_id+start_date. |
| START_DATE | DATE(7) | not null | | A not null column in the complex primary key employee_id+start_date. |
| END_DATE | DATE(7) | not null | | Last day of the employee in this job role. A not null column. Must be |
| JOB_ID | VARCHAR2(10) | not null | | Job role in which the employee worked in the past; foreign key to |
| DEPARTMENT_ID | NUMBER(4, 0) | null | | Department id in which the employee worked in the past; foreign key to deparment_id column in the departments table |