Data analyst internship project: duplicate events versus equal-value purchases

Original invented practice inputs.

Task: A deduplication policy, exception table and revenue reconciliation.

Start with input.json and the CSV tables. Record your method before opening answer-key.json. Keep a changed input and explain how its result differs.

Technical reading:
https://www.sqlite.org/windowfunctions.html

A result from this fixture is independent practice work; describe only work you actually complete.
