[LeetCode/SQL] 1581. Customer Who Visited but Did Not Make Any Transactions

[LeetCode/SQL]

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📌 1581. Customer Who Visited but Did Not Make Any Transactions

문제

풀이

- cutomer_id,와 transaction이 없이 방문한 횟수를 구하라 

방법

SELECT v.customer_id
       ,COUNT(*) AS count_no_trans
FROM Visits AS v
LEFT JOIN Transactions AS t
ON v.visit_id=t.visit_id
WHERE t.visit_id IS NULL
GROUP BY  v.customer_id