Self-Joins

Self Joins are used when a table must be joined to itself to retrieve the data you need. Table aliases are required in the FROM clause to perform self-join

SELECT r.firstname, r.lastname, r.referred, c.lastname "Referred"
FROM customers c, customers r
WHERE  c.referred = r.customer#;
=== Self Joins using the JOIN Method ===
SELECT r.firstname, r.lastname, c.referred, c.lastname "Referred"
FROM customers c JOIN customers r
 ON c.referred = r.customer#;

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