{ "data": { "question": { "questionId": "4103", "questionFrontendId": "3716", "categoryTitle": "Database", "boundTopicId": 3805185, "title": "Find Churn Risk Customers", "titleSlug": "find-churn-risk-customers", "content": "

Table: subscription_events

\n\n
\n+------------------+---------+\n| Column Name      | Type    | \n+------------------+---------+\n| event_id         | int     |\n| user_id          | int     |\n| event_date       | date    |\n| event_type       | varchar |\n| plan_name        | varchar |\n| monthly_amount   | decimal |\n+------------------+---------+\nevent_id is the unique identifier for this table.\nevent_type can be start, upgrade, downgrade, or cancel.\nplan_name can be basic, standard, premium, or NULL (when event_type is cancel).\nmonthly_amount represents the monthly subscription cost after this event.\nFor cancel events, monthly_amount is 0.\n
\n\n

Write a solution to Find Churn Risk Customers - users who show warning signs before churning. A user is considered churn risk customer if they meet ALL the following criteria:

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Return the result table ordered by days_as_subscriber in descending order, then by user_id in ascending order.

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The result format is in the following example.

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Example:

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\n

Input:

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subscription_events table:

\n\n
\n+----------+---------+------------+------------+-----------+----------------+\n| event_id | user_id | event_date | event_type | plan_name | monthly_amount |\n+----------+---------+------------+------------+-----------+----------------+\n| 1        | 501     | 2024-01-01 | start      | premium   | 29.99          |\n| 2        | 501     | 2024-02-15 | downgrade  | standard  | 19.99          |\n| 3        | 501     | 2024-03-20 | downgrade  | basic     | 9.99           |\n| 4        | 502     | 2024-01-05 | start      | standard  | 19.99          |\n| 5        | 502     | 2024-02-10 | upgrade    | premium   | 29.99          |\n| 6        | 502     | 2024-03-15 | downgrade  | basic     | 9.99           |\n| 7        | 503     | 2024-01-10 | start      | basic     | 9.99           |\n| 8        | 503     | 2024-02-20 | upgrade    | standard  | 19.99          |\n| 9        | 503     | 2024-03-25 | upgrade    | premium   | 29.99          |\n| 10       | 504     | 2024-01-15 | start      | premium   | 29.99          |\n| 11       | 504     | 2024-03-01 | downgrade  | standard  | 19.99          |\n| 12       | 504     | 2024-03-30 | cancel     | NULL      | 0.00           |\n| 13       | 505     | 2024-02-01 | start      | basic     | 9.99           |\n| 14       | 505     | 2024-02-28 | upgrade    | standard  | 19.99          |\n| 15       | 506     | 2024-01-20 | start      | premium   | 29.99          |\n| 16       | 506     | 2024-03-10 | downgrade  | basic     | 9.99           |\n+----------+---------+------------+------------+-----------+----------------+\n
\n\n

Output:

\n\n
\n+----------+--------------+------------------------+-----------------------+--------------------+\n| user_id  | current_plan | current_monthly_amount | max_historical_amount | days_as_subscriber |\n+----------+--------------+------------------------+-----------------------+--------------------+\n| 501      | basic        | 9.99                   | 29.99                 | 79                 |\n| 502      | basic        | 9.99                   | 29.99                 | 69                 |\n+----------+--------------+------------------------+-----------------------+--------------------+\n
\n\n

Explanation:

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Result table is ordered by days_as_subscriber DESC, then user_id ASC.

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Note: days_as_subscriber is calculated from the first event date to the last event date for each user.

\n
\n", "translatedTitle": "寻找流失风险客户", "translatedContent": "

表：subscription_events

\n\n
\n+------------------+---------+\n| Column Name      | Type    | \n+------------------+---------+\n| event_id         | int     |\n| user_id          | int     |\n| event_date       | date    |\n| event_type       | varchar |\n| plan_name        | varchar |\n| monthly_amount   | decimal |\n+------------------+---------+\nevent_id 是这张表的唯一主键。\nevent_type 可以是 start，upgrade，downgrade 或 cancel。\nplan_name 可以是 basic，standard，premium 或 NULL（当 event_type 是 cancel）。\nmonthly_amount 表示此次事件后的月度订阅费用。\n对于 cancel 的事件，monthly_amount 为 0。\n
\n\n

编写一个解决方案来 寻找流失风险用户 - 出现预流失信号的用户。如果用户符合以下所有条件，则被视为 有流失风险 的客户：

\n\n\n\n

返回结果表按 days_as_subscriber 降序 排序，然后按 user_id 升序 排序。

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结果格式如下所示。

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示例：

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\n

输入：

\n\n

subscription_events 表：

\n\n
\n+----------+---------+------------+------------+-----------+----------------+\n| event_id | user_id | event_date | event_type | plan_name | monthly_amount |\n+----------+---------+------------+------------+-----------+----------------+\n| 1        | 501     | 2024-01-01 | start      | premium   | 29.99          |\n| 2        | 501     | 2024-02-15 | downgrade  | standard  | 19.99          |\n| 3        | 501     | 2024-03-20 | downgrade  | basic     | 9.99           |\n| 4        | 502     | 2024-01-05 | start      | standard  | 19.99          |\n| 5        | 502     | 2024-02-10 | upgrade    | premium   | 29.99          |\n| 6        | 502     | 2024-03-15 | downgrade  | basic     | 9.99           |\n| 7        | 503     | 2024-01-10 | start      | basic     | 9.99           |\n| 8        | 503     | 2024-02-20 | upgrade    | standard  | 19.99          |\n| 9        | 503     | 2024-03-25 | upgrade    | premium   | 29.99          |\n| 10       | 504     | 2024-01-15 | start      | premium   | 29.99          |\n| 11       | 504     | 2024-03-01 | downgrade  | standard  | 19.99          |\n| 12       | 504     | 2024-03-30 | cancel     | NULL      | 0.00           |\n| 13       | 505     | 2024-02-01 | start      | basic     | 9.99           |\n| 14       | 505     | 2024-02-28 | upgrade    | standard  | 19.99          |\n| 15       | 506     | 2024-01-20 | start      | premium   | 29.99          |\n| 16       | 506     | 2024-03-10 | downgrade  | basic     | 9.99           |\n+----------+---------+------------+------------+-----------+----------------+\n
\n\n

输出：

\n\n
\n+----------+--------------+------------------------+-----------------------+--------------------+\n| user_id  | current_plan | current_monthly_amount | max_historical_amount | days_as_subscriber |\n+----------+--------------+------------------------+-----------------------+--------------------+\n| 501      | basic        | 9.99                   | 29.99                 | 79                 |\n| 502      | basic        | 9.99                   | 29.99                 | 69                 |\n+----------+--------------+------------------------+-----------------------+--------------------+\n
\n\n

解释：

\n\n\n\n

结果表按 days_as_subscriber 降序排序，然后按 user_id 升序排序。

\n\n

注意：days_as_subscriber 按照每个用户的第一个事件日期到最后一个事件日期进行计算。

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