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Date questions test range filtering (a quarter, a year) and truncating timestamps to a month or week for rollups - the bread and butter of reporting queries. They look easy but hide off-by-one traps at range boundaries (inclusive vs exclusive end dates), which is exactly what interviewers probe for. Every analytics-flavored SQL screen includes at least one.
2 problems across 2 schemas · Premium. Each runs your query in an isolated SQLite sandbox with instant, graded feedback.
A quick data question to warm up before you write SQL. No signup needed.
Product data arrives in three normalised source tables: product, subcategory and category. The reporting model needs a single product dimension, and a product's category history must be kept when it changes. How should the data be prepared?
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