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  2. Tuple relational calculus - Wikipedia

    en.wikipedia.org/wiki/Tuple_relational_calculus

    Tuple calculus is a calculus that was created and introduced by Edgar F. Codd as part of the relational model, in order to provide a declarative database-query language for data manipulation in this data model.

  3. Relational calculus - Wikipedia

    en.wikipedia.org/wiki/Relational_calculus

    The relational calculus consists of two calculi, the tuple relational calculus and the domain relational calculus, that is part of the relational model for databases and provide a declarative way to specify database queries.

  4. QUEL query languages - Wikipedia

    en.wikipedia.org/wiki/QUEL_query_languages

    QUEL is a relational database query language, based on tuple relational calculus, with some similarities to SQL.It was created as a part of the Ingres DBMS effort at University of California, Berkeley, based on Codd's earlier suggested but not implemented Data Sub-Language ALPHA.

  5. Relation (database) - Wikipedia

    en.wikipedia.org/wiki/Relation_(database)

    Relation, tuple, and attribute represented as table, row, and column respectively In database theory, a relation , as originally defined by E. F. Codd , [ 1 ] is a set of tuples (d 1 ,d 2 ,...,d n ), where each element d j is a member of D j , a data domain .

  6. Tuple - Wikipedia

    en.wikipedia.org/wiki/Tuple

    A 1-tuple and a 2-tuple are commonly called a singleton and an ordered pair, respectively. The term "infinite tuple" is occasionally used for "infinite sequences". Tuples are usually written by listing the elements within parentheses "( )" and separated by commas; for example, (2, 7, 4, 1, 7) denotes a 5-tuple. Other types of brackets are ...

  7. SQL - Wikipedia

    en.wikipedia.org/wiki/SQL

    SQL deviates in several ways from its theoretical foundation, the relational model and its tuple calculus. In that model, a table is a set of tuples, while in SQL, tables and query results are lists of rows; the same row may occur multiple times, and the order of rows can be employed in queries (e.g., in the LIMIT clause).

  8. Domain relational calculus - Wikipedia

    en.wikipedia.org/wiki/Domain_relational_calculus

    The result of the query is the set of tuples X 1 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).

  9. List of formal systems - Wikipedia

    en.wikipedia.org/wiki/List_of_formal_systems

    Join calculus, a theoretical model for the design of distributed programming languages; π-calculus, a formulation of the theory of concurrent, communicating processes, that was invented by Robin Milner; Relational calculus, a calculus for the relational data model Domain relational calculus; Tuple calculus, inspired the SQL language