Slides (PDF)

The slide deck used in the Week 9 in-class kickoff session. The deck covers: welcome back + recap, the theme ("From moving data to making sense of it"), the chapter-by-chapter tour (Ch1-Ch6), three live exercises from the practice repository, one consolidated live quiz round, career relevance, and the closing hand-written reflection.

<aside> 💡 Use this as a recap. If you missed class or want to re-walk the agenda, the deck mirrors the structure of the lesson: same section numbers, same order. Especially useful for the assignment-launch walk-through (§9) when you start the assignment at home.

</aside>

Download

week_9__presentation.pdf

What's in it

Slides 1-6: Welcome back, the "From moving data to making sense of it" theme, today's agenda, and the assignment frame.
§1 SQL for Analytics: Data locality (SQL vs Python), OLTP vs OLAP workloads.
§2 Joins, CTEs, and Aggregations: Joins, CTEs, aggregations, and Live Exercise 1 (borough aggregation / CTEs).
§3 Data Validation: The four data-validation checks (duplicates, nulls, range, orphaned keys) and Live Exercise 2 (data quality audit).
☕ Break.
§4 OLAP, OLTP & Warehouses: Columnar storage, cloud warehouses, and compute/storage separation.
§5 Data Modeling Concepts: Grain, facts vs dimensions, and the fan-out gotcha.
§6 Building SQL Views: Save queries as views, view vs table freshness, and Live Exercise 3 (views, join-validate).
§7 Live Quiz: One mixed round of 20 questions covering Ch1-Ch6 and gotchas (or run the standalone self-paced version directly in your browser).
Career Relevance & Open Q&A: Week 9 skills in the job market, and CV copy-paste line.
🖊️ Hand-written Closer: Explain views vs querying raw tables directly to a non-technical stakeholder.

The slides are deliberately student-facing only. The teacher's per-section script (pacing, quiz answer cribs, exercise reference solutions, deep-dive default topics, closer rubric) lives in the GitHub-only week_9__lesson_plan.md (visible on GitHub only: not synced to Notion, so no link from this page).

Practice exercises (referenced in the live exercise slides)

Practice exercises live in the HackYourFuture/Learning-Resources/data-track/week-9/ repository.

Section	Practice exercise	What you practice
§2 Live Exercise 1	Ex2: Trips and average fare per borough	`INNER JOIN` + `GROUP BY` + CTEs
§3 Live Exercise 2	Ex6: Validate the raw data	Null, duplicate, and orphaned-key validation
§6 Live Exercise 3	Ex7: Build views, then query them	`CREATE VIEW`, star schema, and join-validation

Reference solutions live in the solutions/ folder of each exercise.

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