The hardest part of joins is remembering which is which. Venn diagrams are used specifically because they solve that problem with the inner/outer/left/right terminology.
His visualizations ultimately help nothing. You have to stare at them for a while to see what the pattern is, but there's absolutely no mnemonic hook to remember what's what, so in the end all you learn from his visualizations are that there exist different ways to slice and dice the products of sets, which is already a given if you're trying to figure out what the differences are.
His visualizations ultimately help nothing. You have to stare at them for a while to see what the pattern is, but there's absolutely no mnemonic hook to remember what's what, so in the end all you learn from his visualizations are that there exist different ways to slice and dice the products of sets, which is already a given if you're trying to figure out what the differences are.