analytics
Applied AI interview questions tagged analytics, across every topic.
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Concepts behind "analytics"
The curriculum that explains the ideas these questions test.
Foundational
Window FunctionsWindow functions compute across a set of rows related to the current row, without collapsing them like GROUP BY does, so you can rank within groups, compute running totals and moving averages, and compare a row to its neighbors (LAG/LEAD), all in one pass. They are the backbone of analytics SQL: top-N-per-group, sessionization, cohort analysis, and period-over-period. Applied-AI interviews probe them because they are the single most-tested SQL skill and the cleanest way to express analytical queries.🗄️ Data & SQL Engineering
Core
Gaps and Islands (Sessionization)Gaps-and-islands is the pattern for grouping consecutive rows into runs (islands) separated by breaks (gaps), the engine behind sessionization, streak detection, and consolidating contiguous ranges. The trick is to assign a group id that stays constant within a run, classically with window functions: ROW_NUMBER differences or LAG-based break flags with a running sum. Applied-AI interviews probe it because sessionizing events (user sessions, activity streaks, contiguous time ranges) is a constant data task and a sharp test of window-function fluency.🗄️ Data & SQL EngineeringSign in