The Vanishing Rows

A medium SQL mock interview question on DataDriven, with an AI interviewer who asks follow-up questions and a hire or no-hire decision at the end.

Domain
SQL
Difficulty
medium
Seniority
L3

Interview Prompt

A downstream dashboard is under-reporting content views, and some views were logged without a user attached. Pair each content view to its user on user_id and return the view's ID, user ID, and username.

Summary

Some records disappear when the tables meet. Figure out why.

How This Interview Works

  1. Read the vague prompt (just like a real interview)
  2. Ask clarifying questions to the AI interviewer
  3. Write and run your SQL against a real database
  4. Answer the interviewer's follow-up questions, then get a hire or no-hire decision