有付款的客户，每人只出现一次

Question

下列查询中，哪些能在不使用 DISTINCT 的情况下，把每位至少有一笔付款的客户恰好列出一次？请选出所有正确的选项。

Answer 1

SELECT c.customer_id, c.last_name FROM customer AS c WHERE c.customer_id IN (SELECT p.customer_id FROM payment AS p);

Answer 2

SELECT c.customer_id, c.last_name FROM customer AS c JOIN payment AS p ON p.customer_id = c.customer_id;

Answer 3

SELECT c.customer_id, c.last_name FROM customer AS c LEFT JOIN payment AS p ON p.customer_id = c.customer_id WHERE p.payment_id IS NOT NULL;

Answer 4

SELECT c.customer_id, c.last_name FROM customer AS c JOIN payment AS p ON p.customer_id = c.customer_id GROUP BY c.customer_id, c.last_name;

Answer 5

SELECT c.customer_id, c.last_name FROM customer AS c WHERE EXISTS (SELECT 1 FROM payment AS p WHERE p.customer_id = c.customer_id);

Answer 6

SELECT c.customer_id, c.last_name FROM customer AS c CROSS JOIN payment AS p WHERE p.customer_id = c.customer_id;

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