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NULL Keys in Joins

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

Interview Prompt

Given two tables where the join key contains some NULL values, write an inner join query and explain what happens to rows where the key is NULL. Show all matching pairs.

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