SELECT c1.first_name || ' ' || c1.last_name, c2.first_name || ' ' || c2.last_name
FROM customer AS c1, customer AS c2
WHERE c1.first_name = c2.last_name — Can also be written as
SELECT c1.first_name || ' ' || c1.last_name, c2.first_name || ' ' || c2.last_name
FROM customer AS c1
JOIN customer AS c2
ON c1.first_name = c2.last_name