Why is 42 a special number?
The number 42 is, in The Hitchhiker's Guide to the Galaxy by Douglas Adams, the "Answer to the Ultimate Question of Life, the Universe, and Everything", calculated by an enormous supercomputer named Deep Thought over a period of 7.5 million years.
This slide deck (with 42 slides) demonstrates a wide variety of SQL statements that should meet almost every common requirement faced by data scientists. The accompanying Google Colab Notebook will allow the user to install Postgres in a free VM and explore variations of these commands. Here is the full course outline for my brand new RDBMS course, complete with all slide decks and notebooks.