Problem
Explain your SQL-first process for turning messy source data into a clean dataset that can power a reliable ABC Education dashboard. Focus on how you inspect data quality, define the target grain, standardize categories and dates, join lookup tables safely, and validate the final output before it reaches a visualization layer.
What This Tests
- Data wrangling in SQL
- Choosing the correct grain for reporting
- Using joins without duplicating rows
- Structuring transformations with CTEs
- Standardizing messy values with CASE WHEN and date functions
Expected Depth
Give a practical workflow rather than a generic analytics answer. The interviewer expects you to describe how you would structure the SQL, what checks you would run, and how you would make the final dataset stable for charts, filters, and recurring refreshes.
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