Broken Promises Between Tables

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

`dq_checks` holds one row per validation run across our tables. Count how many not-null checks failed, returned as a single `fail_count`.

Summary

Every foreign key is a pinky-swear. Count the ones that got broken.

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