Tuesday, August 20, 2013
JOINS and Venn Diagrams
Venn diagrams (an example of which is pictured to the left) are a fairly common way to represent sets and are used a lot in set theory -- and not coincidentally -- in database systems. (Relational databases are based on set theory!)
Today while I was helping out on database administrators stack exchange, I found a good link from Coding Horror that shows a bunch representing Venn diagrams of how JOINs work in SQL. The Venn diagrams themselves don't include the mathematical symbols from set theory, but they are useful nonetheless.