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Joins, filtering, grouping, null semantics, pagination, projections, and practical SQL read queries.
Practice items tagged with SQL Querying Fundamentals.
Pre-aggregates two one-to-many relationships before joining them to prevent fanout from corrupting financial totals.
Builds several daily business metrics in one grouped query while keeping each metric definition explicit.
Uses an ordered window aggregate to calculate a deterministic running balance per account.
Combines daily aggregation, a calendar table, and a window frame to calculate true seven-calendar-day revenue.
Implements correct half-open interval overlap logic for booking validation.
Explains join behavior using API-shaped data, missing related rows, and result-cardinality trade-offs.