Domain calculus

In computer science, domain relational calculus (DRC) is a calculus that was introduced by Michel Lacroix and Alain Pirotte as a declarative database query language for the relational data model.

In DRC, queries have the form:

where each X_i is either a domain variable or constant, and ${\displaystyle p(\langle X_{1},X_{2},....,X_{n}\rangle )}$ denotes a DRC formula. The result of the query is the set of tuples X₁ to X_n that make the DRC formula true.

This language uses the same operators as tuple calculus, the logical connectives ∧ (and), ∨ (or) and ¬ (not). The existential quantifier (∃) and the universal quantifier (∀) can be used to bind the variables.

Its computational expressiveness is equivalent to that of Relational algebra.

Let (A, B, C) mean (Rank, Name, ID) in the Enterprise relation

and let (D, E, F) mean (Name, DeptName, ID) in the Department relation

Find all captains of the starship USS Enterprise:

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