Table Schema
Inspect
Table
| Column | Type |
|---|---|
| user_id | integer |
| subscription_month | date |
Subscription
Retention
Find users who remained subscribed for at least 2 consecutive months.
Inspect
Sample Data
Input
Output
Sample Input: subscriptions
| user_id | subscription_month |
|---|---|
| 101 | 2024-01-01 |
| 101 | 2024-02-01 |
| 102 | 2024-01-01 |
| 103 | 2024-02-01 |
| 104 | 2024-01-01 |
| 104 | 2024-02-01 |
Expected Output
| user_id |
|---|
| 101 |
| 104 |
SQL Editor
Run
Query
Waiting for query
| user_id |
|---|
| 101 |
| 104 |
Hints
Unlock
Clues
Hint 01: Identify the grouping level required by the output.
Hint 02: Aggregate with COUNT, SUM, AVG, or a window function as needed.
Hint 03: Filter after aggregation with HAVING or after ranking with an outer query.
Solution
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Answer
Solution is locked until you decide to reveal it. Try the editor first, then open this when you want the reference answer.
WITH months AS (
SELECT DISTINCT user_id, DATE_TRUNC('month', subscription_month) AS month
FROM subscriptions
),
streaks AS (
SELECT
user_id,
month - (ROW_NUMBER() OVER (PARTITION BY user_id ORDER BY month) * INTERVAL '1 month') AS streak_group
FROM months
)
SELECT user_id
FROM streaks
GROUP BY user_id, streak_group
HAVING COUNT(*) >= 2;Explanation
Step By
Step
01
Read the expected output columns to determine the final grain.
02
Aggregate or rank the input rows to calculate the requested metric.
03
Filter, sort, and alias the final columns to match the output.
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