Welcome to your interview.
The question is on your right: Handling Duplicates and Nulls in SQL. Take a moment with it first.
Talk your thinking through with me if you like - when you're confident, submit your answer and I'll grade it like a real screen (7/10 or better passes). Discussion and graded submissions share your five interviewer interactions, so spend them well.
Data quality issues often show up as duplicate rows and missing values. In analytics and operational systems, both can distort counts, aggregations, and downstream reporting if they are not handled carefully.
Explain how you would handle duplicate records and NULL values in a dataset using SQL. Your answer should cover:
The interviewer expects a practical explanation, not just definitions. Discuss the trade-offs between deleting data, deduplicating in queries, and preventing bad data at ingestion. Use simple SQL examples and mention common mistakes, especially around COUNT, GROUP BY, and comparisons with NULL.