 <p>Personally, I do not rely on implicit conversion. Too often this results in unexpected grief down the road. If asked to provide a filter between a date range, I would be explicit. Pick whatever format you want, but if it might be confusing, then try to eliminate as much of the confusion as possible: </p> <pre><code>SELECT employee_id, first_name, last_name, hire_date FROM employees WHERE hire_date BETWEEN TO_DATE('JAN-01-1980', 'MON-DD-YYYY') AND TO_DATE('JAN-01-1999', 'MON-DD-YYYY') ORDER BY hire_date; </code></pre>