本文共 391 字，大约阅读时间需要 1 分钟。

题目：（中等）

标签：SQL

解法一：

SELECT user_id AS buyer_id,       join_date,       IFNULL(orders_in_2019, 0) AS orders_in_2019FROM Users AS U         LEFT JOIN     (SELECT buyer_id, COUNT(order_id) AS orders_in_2019      FROM Orders      WHERE YEAR(order_date) = 2019      GROUP BY buyer_id) AS T ON U.user_id = T.buyer_id;

转载地址：https://dataartist.blog.csdn.net/article/details/110386357 如侵犯您的版权，请留言回复原文章的地址，我们会给您删除此文章，给您带来不便请您谅解！