Final answer:
Yes, you can use the USING keyword to perform a self-join by matching rows within the same table that have columns with the same name.
Step-by-step explanation:
The question of whether you can use the USING keyword to perform a self-join in a SQL query is a good one. To answer simply: 1) True, the USING keyword can indeed be used to perform a self-join. A self-join is a query in which a table is joined to itself to compare rows within the same table.
The USING keyword comes into play when the columns being joined have the same name in both instances of the table in the query.
An example of a self-join using the USING keyword could be as follows:
SELECT A.name, B.name
FROM employees A
JOIN employees B
USING (manager_id)
WHERE A.employee_id != B.employee_id;
In this example, we're joining the employees table to itself to find pairs of employees who share the same manager. The query uses the manager_id field to match rows from one instance of the employees table (aliased as A) with another (aliased as B).