“SQL Vermeiden Sie Duplikate im Einfügen in Select” Code-Antworten

SQL Vermeiden Sie Duplikate im Einfügen in Select

INSERT INTO OldCustomers(customer_id, age)
SELECT customer_id, age
FROM Customers
WHERE NOT EXISTS(
  SELECT customer_id
  FROM OldCustomers
  WHERE OldCustomers.customer_id = Customers.customer_id
);