Two-Way Street
A medium SQL mock interview question on DataDriven. Practice with AI-powered feedback, real code execution, and a hire/no-hire decision.
- Domain
- SQL
- Difficulty
- medium
- Seniority
- L4
Interview Prompt
In chat_msgs, each reply records the user who wrote it in sender_id and the user being replied to in reply_to, which is empty for messages that are not replies. Count the unique two-person conversations, where a reply from one user to another is the same conversation no matter which of the two sent it.
Summary
A conversation reads the same from either side.
How This Interview Works
- Read the vague prompt (just like a real interview)
- Ask clarifying questions to the AI interviewer
- Write your sql solution with real code execution
- Get instant feedback and a hire/no-hire decision