Use the right tool per layer: Excel for stakeholder models, SQL for warehouse truth, Python for scale and ML.
Flow
- SQL aggregates daily metrics in warehouse
- Export CSV or connect Power Query to database
- Excel pivots/charts for leadership review
- Python notebooks for experiments and production models
Links
Continue on SQL, Data Science, Pandas.
Important interview questions and answers
- Q: Source of truth?
A: Often SQL warehouse—not a emailed xlsx version 7. - Q: Excel role?
A: Presentation and what-if, not petabyte ETL.
Self-check
- Where should metrics be authoritative?
- Excel's role after SQL export?
Tip: Agree which file version is "source of truth" before debating numbers.
Interview prep
- Source of truth?
Often SQL warehouse, not emailed xlsx v7.