How it works: For each join example, there are two tables, the left and the right table, shown as two columns. For the sake of simplicity, these tables are called “a” and “b” respectively in the code.
You’ll notice that the sheet uses a kind of pseudo-code when it comes to table names and column names.
Click through for the PDF. I appreciate that he did not use Venn diagrams, as those should be saved for Union/Intersect/Except.