Guides, cheat sheets and what's new in data.
23 practical, copy-ready resources on SQL, Python, Snowflake, dbt, Power BI, databases and Swift. Free to read, save and print.
What does an analytics engineer do?
The role that sits between raw data and business decisions, explained in plain English.
The data stack in 2026
Fewer tools, more open formats and AI built into the platform. What has changed, and what it means for data teams.
SQL window functions, explained
The single most useful SQL skill after joins. Rankings, running totals and period-over-period comparisons, without self-joins.
SQL joins, explained visually
Every join type in one place, and the one mistake that quietly doubles your revenue figures.
Star schema data modelling
The data model behind fast, trustworthy dashboards. Facts, dimensions and the one decision that matters most: grain.
Your first dbt project, step by step
How analytics engineers turn SQL scripts into tested, documented, version-controlled pipelines.
Getting started with Snowflake
The concepts that make Snowflake different, and the SQL you need on day one.
SQL cheat sheet
Every query pattern you use day to day, on one printable page.
pandas for Excel users
Everything you already do in Excel, translated into Python, and why it scales better.
What's new in Python 3.14
The October 2025 release brought some of the biggest changes to Python in years. Here is what matters for data work.
Python and pandas cheat sheet
The pandas commands analysts use every day, on one printable page.
Data quality tests every pipeline needs
Six checks that catch most data problems before your stakeholders do.
DAX CALCULATE, explained
The most important function in Power BI, explained through the questions it answers.
Snowflake SQL cheat sheet
Snowflake-specific commands and syntax, on one printable page.
Choosing the right database
A clear way to decide, based on what your data is for rather than what is fashionable.
Automate your weekly report
A complete, working pattern for turning a manual weekly report into one that builds itself.
DAX cheat sheet
The DAX patterns behind almost every Power BI report, on one printable page.
Modern Python setup with uv
One fast tool that replaces pip, virtualenv and pyenv for most projects.
JSON in Swift with Codable
The clean, modern way to bring API data into an iPhone app, with no third-party libraries.
What's new in Swift 6.2
Released in September 2025, Swift 6.2 made strict concurrency far easier to live with. Here is what changed.
Swift cheat sheet
Modern Swift syntax at a glance, on one printable page.
From spreadsheets to dashboards
When spreadsheets start costing you time, and what a sensible next step looks like.
Git cheat sheet
The Git commands data teams actually use, on one printable page.
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