Final answer:
The NATURAL JOIN is not suitable for self-joins. Use INNER JOIN instead and specify table alias.
Step-by-step explanation:
The NATURAL JOIN is not suitable for producing a self-join because it matches rows based on all columns with the same name in both tables.
In a self-join, we need to match rows within the same table based on a specific condition, usually involving different columns.
To perform a self-join, we can use the regular INNER JOIN keyword and specify the table alias to differentiate between the main table and the table being joined.