Table Schema
Inspect
Table
| Column | Type |
|---|---|
| song_id | integer |
| stream_date | date |
Trending
Songs
Find songs whose streams increased compared to the previous day.
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Sample Data
Input
Output
Sample Input: streams
| song_id | stream_date |
|---|---|
| 1 | 2024-01-01 |
| 1 | 2024-01-02 |
| 1 | 2024-01-02 |
| 2 | 2024-01-01 |
| 2 | 2024-01-02 |
| 3 | 2024-01-02 |
| 3 | 2024-01-02 |
Expected Output
| song_id |
|---|
| 1 |
SQL Editor
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Query
Waiting for query
| song_id |
|---|
| 1 |
Hints
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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 daily_counts AS (
SELECT song_id, stream_date, COUNT(*) AS frequency
FROM streams
GROUP BY song_id, stream_date
),
with_previous AS (
SELECT
song_id,
stream_date,
frequency,
LAG(frequency) OVER (PARTITION BY song_id ORDER BY stream_date) AS previous_frequency
FROM daily_counts
)
SELECT DISTINCT song_id
FROM with_previous
WHERE frequency > previous_frequency;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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