Editing Domain relational calculus (section)

In [[computer science]], '''domain relational calculus''' ('''DRC''') is a calculus that was introduced by Michel Lacroix and [[Alain Pirotte]] as a [[declarative programming|declarative]] [[query language|database query language]] for the [[relational model|relational data model]].<ref name="LP77">Michel Lacroix, Alain Pirotte: [https://dl.acm.org/citation.cfm?id=1286620 Domain-Oriented Relational Languages]. VLDB 1977: 370-378</ref>

In DRC, ''queries'' have the form:

:<math> \{\langle X_1, X_2, ...., X_n \rangle \mid p(\langle X_1, X_2, ...., X_n\rangle) \} </math>

where each X<sub>i</sub> is either a domain variable or constant, and <math>p(\langle X_1, X_2, ...., X_n \rangle)</math> denotes a DRC ''formula''.  The result of the query is the set of tuples X<sub>1</sub> to X<sub>n</sub> that make the DRC formula true.

This language uses the same operators as [[tuple calculus]],
the logical connectives &and; (and), &or; (or) and ¬ (not). The [[existential quantification|existential quantifier]] (∃) and the [[universal quantification|universal quantifier]] (∀) can be used to bind the variables.

Its computational expressiveness is equivalent to that of [[relational algebra]].<ref name="Codd72a">[[E. F. Codd]]: [http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.444.3426&rep=rep1&type=pdf Relational Completeness of Data Base Sub-languages]. In R. Rustin, editor, Data Base Systems. Prentice Hall, 1972</ref>