LeetCode in Kotlin

3497. Analyze Subscription Conversion

Medium

Table: UserActivity

+------------------+---------+
| Column Name      | Type    |
+------------------+---------+
| user_id          | int     |
| activity_date    | date    |
| activity_type    | varchar |
| activity_duration| int     |
+------------------+---------+
(user_id, activity_date, activity_type) is the unique key for this table. activity_type is one of ('free_trial', 'paid', 'cancelled').
activity_duration is the number of minutes the user spent on the platform that day.
Each row represents a user's activity on a specific date. 

A subscription service wants to analyze user behavior patterns. The company offers a 7-day free trial, after which users can subscribe to a paid plan or cancel. Write a solution to:

1. Find users who converted from free trial to paid subscription
2. Calculate each user’s average daily activity duration during their free trial period (rounded to 2 decimal places)
3. Calculate each user’s average daily activity duration during their paid subscription period (rounded to 2 decimal places)

Return the result table ordered by user_id in ascending order.

The result format is in the following example.

Example:

Input:

UserActivity table:

user_id	activity_date	activity_type	activity_duration
1	2023-01-01	free_trial	45
1	2023-01-02	free_trial	30
1	2023-01-05	free_trial	60
1	2023-01-10	paid	75
1	2023-01-12	paid	90
1	2023-01-15	paid	65
2	2023-02-01	free_trial	55
2	2023-02-03	free_trial	25
2	2023-02-07	free_trial	50
2	2023-02-10	cancelled	0
3	2023-03-05	free_trial	70
3	2023-03-06	free_trial	60
3	2023-03-08	free_trial	80
3	2023-03-12	paid	50
3	2023-03-15	paid	55
3	2023-03-20	paid	85
4	2023-04-01	free_trial	40
4	2023-04-03	free_trial	35
4	2023-04-05	paid	45
4	2023-04-07	cancelled	0

Output:

user_id	trial_avg_duration	paid_avg_duration
1	45.00	76.67
3	70.00	63.33
4	37.50	45.00

Explanation:

• User 1:
  • Had 3 days of free trial with durations of 45, 30, and 60 minutes.
  • Average trial duration: (45 + 30 + 60) / 3 = 45.00 minutes.
  • Had 3 days of paid subscription with durations of 75, 90, and 65 minutes.
  • Average paid duration: (75 + 90 + 65) / 3 = 76.67 minutes.
• User 2:
  • Had 3 days of free trial with durations of 55, 25, and 50 minutes.
  • Average trial duration: (55 + 25 + 50) / 3 = 43.33 minutes.
  • Did not convert to a paid subscription (only had free_trial and cancelled activities).
  • Not included in the output because they didn’t convert to paid.
• User 3:
  • Had 3 days of free trial with durations of 70, 60, and 80 minutes.
  • Average trial duration: (70 + 60 + 80) / 3 = 70.00 minutes.
  • Had 3 days of paid subscription with durations of 50, 55, and 85 minutes.
  • Average paid duration: (50 + 55 + 85) / 3 = 63.33 minutes.
• User 4:
  • Had 2 days of free trial with durations of 40 and 35 minutes.
  • Average trial duration: (40 + 35) / 2 = 37.50 minutes.
  • Had 1 day of paid subscription with duration of 45 minutes before cancelling.
  • Average paid duration: 45.00 minutes.

The result table only includes users who converted from free trial to paid subscription (users 1, 3, and 4), and is ordered by user_id in ascending order.

Solution

# Write your MySQL query statement below
SELECT
    ft.user_id,
    ROUND(ft.avg_trial, 2) AS trial_avg_duration,
    ROUND(pt.avg_paid, 2) AS paid_avg_duration
FROM
    (SELECT user_id, AVG(activity_duration) AS avg_trial
     FROM UserActivity
     WHERE activity_type = 'free_trial'
     GROUP BY user_id) ft
JOIN
    (SELECT user_id, AVG(activity_duration) AS avg_paid
     FROM UserActivity
     WHERE activity_type = 'paid'
     GROUP BY user_id) pt
ON ft.user_id = pt.user_id
ORDER BY ft.user_id ASC;

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