Welcome to your interview.
The question is on your right: Classify Orders with CASE WHEN. 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.
Teams often need to categorize rows, clean outputs, or build conditional metrics directly in SQL. CASE WHEN is one of the most common tools for adding business logic to a query without changing the underlying data.
Explain how you would use CASE WHEN in a SQL query. In your answer, cover:
CASE WHEN doesSELECT, WHERE, and ORDER BYNULL values interact with CASE WHENThe interviewer expects a practical explanation with simple PostgreSQL examples. You should describe the syntax, common use cases, and a few mistakes to avoid, rather than giving a highly theoretical answer.