Calculate Rolling 7-Day Sum of Answers by Device

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PracHub provides an interactive SQL console where you can write and test queries against real database schemas. Get instant feedback and compare your solution with the expected output.

Q: What difficulty level is this coding question?

This is a Medium difficulty Data Manipulation (SQL/Python) question, commonly asked during Onsite rounds at Amazon.

Q: What role is this question designed for?

This question is commonly asked for Business Intelligence Engineer candidates at Amazon during technical interviews.

Question

ANSWERS

+------------+--------+---------+
| date       | device | answers |
+------------+--------+---------+
| 2019-01-01 | echo   | 10      |
| 2019-01-02 | echo   | 20      |
| 2019-01-03 | echo   | 30      |
| 2019-01-01 | dot    | 10      |
| 2019-01-02 | dot    | 15      |
+------------+--------+---------+

##### Scenario

Voice-assistant analytics team needs to monitor recent engagement per device type.

##### Question

Given table ANSWERS(date, device, answers), write a query returning (date, device, trailing_7d_answers) where trailing_7d_answers is the rolling 7-day sum of answers for each device, ordered by date.

##### Hints

Use window functions with PARTITION BY device and a 7-day RANGE or conditional SUM over preceding rows.

PracHub · Accepted Answer

This question evaluates proficiency in time-series aggregation and group-wise metric computation on structured data, specifically calculating rolling seven-day sums of answers per device, and assesses familiarity with data manipulation using SQL or Python.

Quick Overview

Calculate Rolling 7-Day Sum of Answers by Device