The Library · Insights
Deep dives across data, automation & AI
984 in-depth articles — from Excel foundations to production machine learning. Filter by topic or difficulty to find exactly what you need.
Power QueryPractitioner
Splitting and Processing Fixed-Width and Delimited Text Files in Power Query: Parsing Legacy Flat File Formats
Legacy flat files from mainframes, ERPs, and AS/400 systems don't cooperate with Power Query's default import wizard. This lesson teaches you how to parse fixed-width and non-standard delimited formats with full control — from raw binary loading to reusable, dynamic parsers.
21 min read
Microsoft ExcelPractitioner
Building a Dynamic Excel Dashboard with VBA: Automate Charts, Slicers, and KPI Summaries That Update on Demand
Static dashboards are a maintenance burden. This hands-on lesson walks you through building a fully automated Excel dashboard using VBA — with programmatic slicer control, event-driven KPI tiles, and chart routines that handle changing data without breaking. By the end, you'll have production-ready code and a three-layer workbook architecture you can reuse on any project.
22 min read
Career DevelopmentFoundation
How to Write a Freelance Data Services Contract From Scratch: Key Clauses, Plain-English Templates, and What to Include Before You Take On Your First Client
Most data freelancers lose money not because of bad work, but because of bad contracts. This lesson walks you through every clause you need — scope, payment, IP, confidentiality, and more — with plain-English templates you can adapt today.
17 min read
Career DevelopmentFoundation
How to Choose Your First Data Tool to Learn: Python vs SQL vs Excel Based on the Role You Want
Most advice tells you to "just learn Python" — but that's wrong if you're targeting a business analyst or reporting role. This lesson shows you exactly which tool to learn first based on the actual job you want, with a real decision framework backed by job market research.
18 min read
Data EngineeringFoundation
Scheduling and Backfilling Historical Data Loads in Airflow: Catchup, DAG Runs, and Idempotent Pipeline Design
Learn how Airflow's interval-based scheduling model really works — and how to safely backfill months of historical data without duplicating records. This hands-on lesson covers catchup behavior, the backfill CLI, and the idempotent design patterns every data pipeline needs.
16 min read
Data EngineeringFoundation
Understanding Data Pipeline Triggers: Time-Based, Event-Driven, and Sensor Patterns
Knowing when your pipeline should run is just as important as knowing what it should do. This lesson breaks down the three core trigger patterns — cron schedules, event-driven triggers, and sensors — with real code examples and a decision framework you can use immediately.
17 min read
AI & Machine LearningFoundation
Document Ingestion Pipelines: Loading, Cleaning, and Preprocessing Text for RAG
Before your RAG system can answer questions intelligently, it needs clean, well-structured text to work with. This hands-on lesson walks you through building a complete document ingestion pipeline in Python — from loading PDFs and Word files to cleaning noise, chunking text, and enriching chunks with metadata.
15 min read
AI & Machine LearningFoundation
Conversation Design for LLMs: Structuring System Prompts, Roles, and Message Threads with the Chat Completions API
Most LLM applications fail not because the model is wrong, but because the conversation is designed poorly. Learn how to structure system prompts, manage multi-turn message threads, and inject dynamic context using the Chat Completions API — the skills every serious LLM builder needs.
15 min read
AI & Machine LearningFoundation
From Vague to Precise: How to Diagnose and Fix Prompts That Return Unhelpful AI Responses
Most AI responses that miss the mark aren't the AI's fault — they're the prompt's fault. This lesson teaches you a five-point diagnostic framework to identify exactly why your prompt failed and apply targeted fixes that get you useful, precise answers every time.
16 min read
SQLFoundation
Datetime Arithmetic and Interval Calculations in SQL: Converting, Truncating, and Computing Durations Across Database Platforms
Dates and times are everywhere in data work, but SQL's datetime functions vary wildly across platforms — and the edge cases produce wrong answers that look right. This lesson teaches you how to cast, truncate, and subtract dates, and how to use interval arithmetic across PostgreSQL, MySQL, BigQuery, and SQL Server.
14 min read
Power AutomateFoundation
Getting Started with the Power Automate Interface: Navigating the Designer, Understanding Flow Structure, and Running Your First Test
Power Automate can feel overwhelming before you know where everything lives. This hands-on lesson walks you through the designer, explains how triggers and actions work together, and gets you building and testing a real flow from scratch — no prior experience required.
16 min read
Power AppsFoundation
Power Apps Data Sources Explained: Tables, Records, and Collections for Absolute Beginners
Confused about where data lives in Power Apps and how to work with it? This lesson builds your understanding from first principles — covering tables, records, fields, external data sources, and collections — so you can confidently connect data to any app you build.
15 min read