If you want to go that far, then learn about the non-portable and vendor-specific (Oracle, Postgres, etc.) parts of SQL.

Relational Algebra helps with designing fast tables.

> calculus

Did you mean what is commonly referred to as "calculus" or specifically "Relational Calculus" as opposed to Relational Algebra?

"Common calculus" is not connected in any obvious way where it might help. Most of the Lyapunov stuff is kind if obvious for discrete database tables, too. I know very good database people who just ignored all of calculus (except for modelling problem domains).