MySQL select 值在范围内，而该值不在另一个范围内

Question

我们有一个 table 记录每个客户请求，每个请求都有一个 created_at 和 customer_email 列。

mysql> select * from requests;

+---------------------+-----------------------+
| created_at          | customer_email        |
+---------------------+-----------------------+
| 2016-08-08 14:05:50 | user1@example.com     |
| 2016-08-08 14:05:51 | user2@example.com     |
| 2017-08-15 14:41:40 | user3@example.com     |
| 2017-08-15 15:17:25 | user2@example.com     |
| 2018-08-15 15:30:41 | user1@example.com     |
+---------------------+-----------------------+

我正在尝试获取 08/2018 中 created_at 的 customer email 的记录，但在此之前没有创建请求。换句话说，找出哪些在 08/2018 中创建请求的客户是新客户。
这是我正在尝试的查询，它返回 0

    SELECT DISTINCT
    customer_email
FROM
    requests
WHERE
    created_at > '2018-08-01'
        AND customer_email NOT IN (SELECT DISTINCT
            customer_email
        FROM
            requests
        WHERE
            created_at < '2018-08-01')

如有任何帮助，我们将不胜感激！

Answer 1

尝试使用 GROUP BY 和 HAVING 子句。

使用 MIN function, we can find out the first_created_at for a customer_email, and then utilizing HAVING 子句，我们将结果集限制为在 08/18.

之后具有 first_created_at 的结果集

SELECT customer_email, DATE(MIN(created_at)) AS first_created_at 
FROM requests
GROUP BY customer_email 
HAVING first_created_at >= DATE('2018-08-01')

MySQL select 值在范围内，而该值不在另一个范围内

MySQL select value in range where that value not in another range

mysql

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