Lacroix and Pirotte proposed domain calculus, which is closer to first-order logic and which showed that both of these calculi (as well as relational algebra) are equivalent in expressive power.
Calculus | The Calculus Affair | Relational database management system | Calculus (AB & BC) | calculus | relational database | relational database management system | Itō calculus | Calculus of variations | Tuple | tuple | relational (grammar) | Relational database | Relational | Regge calculus | Professor Calculus | vector calculus | tuple space | Rod calculus | Relational psychoanalysis | relational | operational calculus | Object-relational impedance mismatch | Multivariable Calculus | Multivariable calculus | Microsoft's relational database management system | Ito Calculus | Fundamental lemma of calculus of variations | calculus of variations | Calculus of communicating systems |