task: #3497

Author: Ivanbyone

README.md

@@ -174,6 +174,7 @@ Useful for preparing for technical interviews and improving your SQL skills.
     - [1907. Count Salary Categories](./leetcode/medium/1907.%20Count%20Salary%20Categories.sql)
     - [1934. Confirmation Rate](./leetcode/medium/1934.%20Confirmation%20Rate.sql)
     - [3475. DNA Pattern Recognition](./leetcode/medium/3475.%20DNA%20Pattern%20Recognition.sql)
+    - [3497. Analyze Subscription Conversion](./leetcode/medium/3497.%20Analyze%20Subscription%20Conversion.sql)
 3. [Hard](./leetcode/hard/)
     - [185. Department Top Three Salaries](./leetcode/hard/185.%20Department%20Top%20Three%20Salaries.sql)
     - [3374. First Letter Capitalization II](./leetcode/hard/3374.%20First%20Letter%20Capitalization%20II.sql)

leetcode/medium/3497. Analyze Subscription Conversion.sql

@@ -0,0 +1,56 @@
+/*
+Question 3497. Analyze Subscription Conversion 
+Link: https://leetcode.com/problems/analyze-subscription-conversion/description/?envType=problem-list-v2&envId=database
+
+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:
+
+Find users who converted from free trial to paid subscription
+Calculate each user's average daily activity duration during their free trial period (rounded to 2 decimal places)
+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.
+*/
+
+WITH trial_durations AS (
+    SELECT
+        user_id,
+        AVG(activity_duration) AS trial_avg_duration
+    FROM UserActivity
+    WHERE activity_type = 'free_trial'
+    GROUP BY user_id
+),
+
+paid_duration AS (
+    SELECT
+        user_id,
+        AVG(activity_duration) AS paid_avg_duration
+    FROM UserActivity
+    WHERE activity_type = 'paid'
+    GROUP BY user_id
+)
+
+SELECT DISTINCT
+    u.user_id,
+    ROUND(t.trial_avg_duration, 2) AS trial_avg_duration,
+    ROUND(p.paid_avg_duration, 2) AS paid_avg_duration
+FROM UserActivity AS u
+INNER JOIN 
+    trial_durations AS t
+    ON u.user_id = t.user_id
+INNER JOIN
+    paid_duration AS p
+    ON u.user_id = p.user_id
+