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The Querynomicon

I always felt that every well-rounded developer needs to build a strong working knowledge of SQL.

You don’t need to know the internals of the query engine of your chosen DBMS.1 You don’t need to master the arcane depths of proprietary SQL syntax. However, you should know the types of joins, how NULLs are dealth with, what a SARGable2 condition is and how to write it, and most importantly, how to think about your data in sets.

A long time ago I wrote about some of the tools and resources I used to learn SQL. I was also blessed to work at a company which put data first, where one developer had forgotten more about SQL and Windows internals than most people will ever learn. So I had access to a lot of tools and immersion in an environment that would be difficult for some to find. My unstructured approach to learning was not so different from total immersion plus comprehensive input, in the world of second language acquisition; that is, I would have had to try in order to not learn SQL.

Today I came across a new resource for learning SQL that would have been incredible back when I was still learning the ropes: The Querynomicon. 3

This site is not only a great resource, it is built wonderfully. Starting with a quick overview, then onto scope (intended audience, prerequisites, and learning outcomes), then straight onto learning peppered with practice exercises, then wrapping up with a concise yet comprehensive glossary, I’m just impressed by the level of quality here. From the structure to the presentation, it’s impeccably laid out, almost like a condensed textbook turned hypertext.4 You could turn this site into a class! Even the flowcharts, explaining high-level concepts, are masterfully done and read like natural language. I love it.

If you’re slightly familiar with SQL, this really is a great site to check out. If you’re brand-new and want to begin learning, maybe start with SQL Server Central’s Stairway to Data (or DML) series, and then the Querynomicon to reinforce what you’ve learned.

  1. Database Management System.
  2. SARGable is short for ‘Search ARGument ABLE’; in short, it means your query can easily take advantage of an index. Imagine yourself flipping through a dictionary searching for words that start with s vs. words that contain s — one is going to be a whole lot easier, both for you and your database engine.
  3. Edit 2025: Original link is dead; updated the link to the github repo instead.
  4. No surprise, since it’s essentially lecturer’s notes.

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