Validate Customer-Facing Dataset Quality

Context

Before sharing data with a customer, analysts need to confirm that the dataset is accurate, complete, and internally consistent. Interviewers ask this to assess whether you can combine SQL checks with sound data validation habits.

Core Question

Explain how you would verify that a dataset is clean and trustworthy before presenting it to a customer. Your answer should cover:

1. The main categories of checks you would run in SQL
2. How you would identify issues like duplicates, nulls, invalid values, and unexpected aggregates
3. How you would validate results against business expectations or source systems
4. What you would do if you found data quality problems

Scope Guidance

Keep the answer practical and SQL-focused. The interviewer is not looking for a complex pipeline design; they want a clear framework for validating a dataset, examples of simple PostgreSQL checks, and a structured explanation of how you would build confidence before presenting results.