Loading interview...

Join Type Row Counts

A easy SQL mock interview question on DataDriven. Practice with AI-powered feedback, real code execution, and a hire/no-hire decision.

Domain
SQL
Difficulty
easy
Seniority
junior, mid

Interview Prompt

Using the users and ad_impressions tables, write a single query that returns the row count produced by each combination type: inner, left, and full outer. Some users have no impressions, and some impressions have no associated user. Return each type as a label alongside its row count.

How This Interview Works

  1. Read the vague prompt (just like a real interview)
  2. Ask clarifying questions to the AI interviewer
  3. Write your sql solution with real code execution
  4. Get instant feedback and a hire/no-hire decision