Editing Tuple relational calculus (section)

{{Short description|Relational model}}
'''Tuple calculus''' is a [[wikt:calculus|calculus]] that was created and introduced by [[Edgar F. Codd]] as part of the [[relational model]], in order to provide a [[Declarative programming|declarative]] database-query language for data manipulation in this [[data model]]. It formed the inspiration for the database-query languages [[QUEL query languages|QUEL]] and [[SQL]], of which the latter, although far less faithful to the original relational model and calculus, is now the de facto standard database-query language; a dialect of SQL is used by nearly every [[relational database management system|relational-database-management system]]. Michel Lacroix and Alain Pirotte proposed [[domain calculus]], which is closer to [[First-order predicate calculus|first-order logic]] and together with Codd showed that both of these calculi (as well as [[relational algebra]]) are equivalent in [[expressive power (computer science)|expressive power]].{{cn|date=April 2025}} Subsequently, query languages for the relational model were called ''relationally complete'' if they could express at least all of these queries.