Rank Ads by Conversion Rate for Top 10 Performers

Q: How do I practice SQL interview questions?

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 Meta.

Q: What role is this question designed for?

This question is commonly asked for Data Scientist candidates at Meta during technical interviews.

Question

ad

id | advertiser_id | created_at

1  | 101           | 2023-07-01

2  | 102           | 2023-07-05

3  | 101           | 2023-07-10

​

impression

id | ad_id | user_id | timestamp

10 | 1     | 555     | 2023-07-11 10:00

11 | 1     | 556     | 2023-07-11 10:05

12 | 2     | 557     | 2023-07-12 09:00

​

conversion

id | impression_id | revenue | timestamp

100 | 10           | 5.00    | 2023-07-11 10:10

101 | 12           | 10.00   | 2023-07-12 09:15

##### Scenario

Advertising platform wants to track ad effectiveness over the last 30 days.

##### Question

Given tables ad, impression and conversion, write SQL to return for every ad_id: total impressions, total conversions, conversion_rate and total_revenue for the past 30 days. Extend the query to rank ads by conversion_rate and return the top 10 performers.

##### Hints

Think joins (impression → conversion), date filters, group-by ad_id, and safe division for rates.

PracHub · Accepted Answer

This question evaluates data manipulation and analytics skills for computing time-windowed ad performance metrics, including aggregations of impressions and revenue, join logic between impression and conversion records, conversion-rate calculation, and ranking.

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