The Library · Insights
Deep dives across data, automation & AI
1263 in-depth articles — from Excel foundations to production machine learning. Filter by topic or difficulty to find exactly what you need.
AI & Machine LearningPractitioner
Few-Shot and Zero-Shot Prompting: When and How to Use Examples to Improve AI Output Quality
Most AI prompts underperform because they rely on instructions when they should be using examples. This lesson teaches you the mechanics of few-shot prompting, how to design example sets strategically, and how to debug the most common failure modes — with complete, production-ready prompts for data workflows.
20 min read
SQLPractitioner
Lateral Joins and CROSS APPLY: Row-by-Row Subquery Power in SQL
Standard SQL joins can't reference the current outer row inside a subquery — lateral joins and CROSS APPLY break that limitation wide open. Learn how they work, when to use them, and how to write them for real-world data transformation problems across PostgreSQL, SQL Server, MySQL, and BigQuery.
23 min read
Power AutomatePractitioner
Handling Pagination and Throttling When Querying Large Datasets in Power Automate
Most Power Automate flows silently return incomplete data because they don't handle pagination — or they crash against API rate limits with no recovery. This lesson teaches you how pagination and throttling actually work, and how to build production-grade flows that retrieve complete datasets reliably.
21 min read
Power AppsPractitioner
Power Apps Collections and Local Data Management: Mastering ClearCollect, Patch, and In-Memory Data Operations
Most Power Apps developers only scratch the surface of collections. This lesson teaches you how to architect a full local data management layer — using ClearCollect, Patch, UpdateIf, and SaveData — to build offline-capable, batch-submitting, production-grade Canvas Apps. Includes a complete hands-on inspection app exercise.
19 min read
Power BIPractitioner
Implementing Power BI Aggregations to Optimize Query Performance on Billion-Row Enterprise Datasets
Slow DirectQuery dashboards on massive fact tables aren't a hardware problem — they're an architecture problem. This lesson walks you through building a complete Power BI aggregation layer that routes common analytical queries to fast in-memory pre-summaries while preserving drill-through access to full granular detail.
21 min read
Power BIPractitioner
Building Statistical Measures in DAX: Percentiles, Standard Deviation, and Outlier Detection for Analytical Reporting
Move beyond basic aggregations and build a complete statistical toolkit in DAX. This hands-on lesson walks you through percentile calculations, standard deviation, Z-scores, and IQR-based outlier detection—with production-ready formulas and real-world business scenarios.
18 min read
Power BIPractitioner
Mastering Time Intelligence in Power BI: Building YTD, MTD, and Period-over-Period DAX Measures
Time intelligence is what transforms a static Power BI report into a living analysis — but most practitioners get it subtly wrong. This lesson walks you through building a complete, production-ready suite of YTD, MTD, and period-over-period measures from scratch, including fiscal calendar support and partial period handling.
19 min read
Power QueryPractitioner
Streaming and Pagination Patterns in M: Handling Large APIs and Multi-Page Data Sources with Custom Iterators
Most Power Query tutorials stop at fetching one page of API data. This lesson goes all the way — teaching you how to build robust, production-ready pagination handlers in M that work across offset-based, cursor-based, and link-header APIs using List.Generate and custom iterators. You'll leave with reusable code and a mental model that makes any paginated API manageable.
21 min read
Power QueryPractitioner
Unpacking Nested JSON and XML Structures in Power Query: Expanding Lists, Records, and Tables
Most real-world APIs and data files are nested — JSON objects inside arrays inside objects, XML elements three levels deep. This lesson teaches you how to systematically expand Lists, Records, and Tables in Power Query, handle multi-level nesting, and write M code that doesn't break when the source schema changes.
22 min read
Career DevelopmentFoundation
Qualifying Freelance Data Clients Before You Pitch: Red Flags, Budget Signals, and the Discovery Call Framework
Most freelancers lose hours pitching to clients who were never going to hire them. This lesson teaches you how to read early signals, run a structured discovery call, and spot the red flags that predict painful engagements — before you write a single proposal.
16 min read
Data EngineeringFoundation
Setting Up Your First Cloud Data Warehouse: A Hands-On Guide to Snowflake or BigQuery Free Tier
Stop manually stitching together CSVs and spreadsheets. This hands-on lesson walks you through setting up a real cloud data warehouse in Snowflake or BigQuery — for free — loading actual e-commerce data, and writing your first analytical SQL queries from scratch.
16 min read
Data EngineeringFoundation
Data Pipeline Design Patterns: Fan-Out, Fan-In, and Branching Workflows Explained
Real data pipelines rarely move in straight lines. Learn the three foundational patterns — fan-out, fan-in, and branching — that govern how data flows through production pipelines, with hands-on Python examples and realistic scenarios.
16 min read