Lessons
1SQL mental model: grain, order, nulls48 min read
Execution order, grain discipline, bag vs set, three-valued logic, and the narration OS interviewers grade before fancy windows.
- →SQL Reasoning and Debugging
2Joins & nulls under interview pressure48 min read
INNER/LEFT/FULL/CROSS, semi and anti joins, ON vs WHERE, null keys, chasm traps, and existence patterns that avoid fan-out.
- →Joins and Row Sets
3Aggregations & metric definitions48 min read
GROUP BY discipline, FILTER/CASE aggregates, distinct metrics, weighted ratios, ROLLUP awareness, and date spines.
- →Reliable Aggregations
4Window functions & framing50 min read
ROW_NUMBER/RANK, LAG/LEAD, running totals, ROWS vs RANGE traps, QUALIFY, sessionization sketch, top-N per group.
- →Window Analysis
5CTEs, recursion & SQL debugging48 min read
Staged CTE style, materialization caveats, recursive hierarchies, fan-out detectors, broken-query clinic, EXPLAIN altitude.
- →SQL Reasoning and Debugging
6OLTP schema design interviews50 min read
Keys, normalization vs denorm, N:M bridges, soft delete, multi-tenant pool indexes, money types, and a worked trips schema.
- →Transactional Schema Design
7Warehouse facts, dims & events50 min read
Star schema, additive vs semi-additive measures, SCD2 point-in-time, funnels, conformed dims, partitioning and incremental loads.
- →Analytics Modeling
8Capstone: live SQL + modeling mock55 min read
Integrated marketplace mock: monthly GMV/buyers, first vs repeat, top category windows, refunds schema, warehouse grains, and a six-axis hire rubric.
- →SQL Reasoning and Debugging
- →Window Analysis
- →Analytics Modeling
Skills in this course
- 01SQL Reasoning and DebuggingState grain, execution order, NULL behavior, and debug complex queries methodically.
- 02Joins and Row SetsChoose joins, semi-joins, anti-joins, and keys without fan-out or NULL mistakes.
- 03Reliable AggregationsBuild counts, ratios, time buckets, and grouped metrics at a clear grain.
- 04Window AnalysisUse ranking, lag, running metrics, and explicit frames correctly.
- 05Transactional Schema DesignModel identity, cardinality, history, tenancy, and indexes from access paths.
- 06Analytics ModelingDesign facts, dimensions, measures, history, events, and incremental loads.