here are some other graphical illustrations of the operators from relational algebra - http://bandilab.org/bandicoot-algebra.pdf http://bandilab.org/bandicoot-a

here are some other graphical illustrations of the operators from relational algebra - http://bandilab.org/bandicoot-algebra.pdf http://bandilab.org/bandicoot-algebra.pdf It's focusing on bandicoot language, but concepts are taken from the relational algebra. It should match the logic of SQL.