Tuple relational calculus

<p>Tuple calculus is a calculus that was created and introduced by <a href="/facts/Edgar_F._Codd/QCSbPYkK">Edgar F. Codd</a> as part of the <a href="/facts/Relational_model/VFf4dDIU">relational model</a>, in order to provide a <a href="/facts/Declarative_programming/gogtdzcJ">declarative</a> database-query language for data manipulation in this <a href="/facts/Data_model/j1YyzpJ3">data model</a>. It formed the inspiration for the database-query languages <a href="/facts/QUEL_query_languages/3uGE8f84">QUEL</a> and <a href="/facts/SQL/UjQLJcYm">SQL</a>, 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 <a href="/facts/Relational_database_management_system/pEKGmJLy">relational-database-management system</a>. Michel Lacroix and Alain Pirotte proposed <a href="/facts/Domain_calculus/lwXJ4xEU">domain calculus</a>, which is closer to <a href="/facts/First-order_predicate_calculus/lcISqWIg">first-order logic</a> and together with Codd showed that both of these calculi (as well as <a href="/facts/Relational_algebra/7tjTFXdf">relational algebra</a>) are equivalent in <a href="/facts/Expressive_power_(computer_science)/DEp1sAtc">expressive power</a>. Subsequently, query languages for the relational model were called <i>relationally complete</i> if they could express at least all of these queries.
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Tuple relational calculus open-in-new

Tuple relational calculus