ByteDance Data Scientist Interview Experience — 40-Minute Phone Screen with a Resume Project and Three SQL Questions

TikTok technical phone screen. It was scheduled for an hour but actually ran about 40 minutes.

We introduced ourselves to each other first, and then talked about one project on my resume. I went through it in detail and the interviewer asked a few follow-up questions.

After that came SQL, two tables and three questions:

daily_log: date, user_id, app_id, country, event_type.

user_risk: date, user_id, country, risk_score, num_sessions.

• Find the non-US countries where the number of video-watch events in a given time period reached 1,000.
• Count today's DAU for each app_id, excluding the US, and only counting non-fraudulent users, meaning users with risk_score <= 3 that day.
• Count today's video-watch events for each app_id x country, excluding the US. The output also needs the average daily fraudulent sessions (risk_score > 3) per country over the past 30 days, and the countries need to be ranked by it.