In database theory, relational algebra is a theory that uses algebraic structures for modeling data and defining queries on it with well founded semantics...

In relational algebra, a selection (sometimes called a restriction in reference to E.F. Codd's 1970 paper and not, contrary to a popular belief, to avoid...

Selection (relational algebra) Selection-based search, a search engine system in which the user invokes a search query using only the mouse Selection...

In relational algebra, a join is a binary operation, written as R ⋈ S {\displaystyle R\bowtie S} where R {\displaystyle R} and S {\displaystyle S} represent...

In database theory, Imieliński–Lipski algebra is an extension of relational algebra onto tables with different types of null values. It is used to operate...

A relational database (RDB) is a database based on the relational model of data, as proposed by E. F. Codd in 1970. A Relational Database Management System...

and algebraic description of models appropriate for the study of various logics (in the form of classes of algebras that constitute the algebraic semantics...

represents the set of symbols that form an alphabet (see also linguistics) Relational algebra uses the values σ a θ b ( R ) {\displaystyle \sigma _{a\theta b}(R)}...

specifies which rows to retrieve. This is approximately the relational algebra selection operation. GROUP BY groups rows sharing a property so that an...

related to query languages for relational databases, such as SQL. The following table maps between Datalog, relational algebra, and SQL concepts: More formally...

developed since 1970 in connection with molecular set theory, relational biology and algebraic biology. A monograph on this topic summarizes an extensive...

SQLf is the multi-relational block. The conception of this structure is based on the three basic operations of the relational algebra: projection, cartesian...

have the same arithmetic operators and all can be overloaded in C++. All relational (comparison) operators can be overloaded in C++. Since C++20, the inequality...

notable theorems. Lists of theorems and similar statements include: List of algebras List of algorithms List of axioms List of conjectures List of data structures...

history; particularly, the history of science. In 1959 he obtained a PhD in relational biology, a specialization within the broader field of Mathematical Biology...

in the development of relational databases that recursive queries cannot be expressed in either relational algebra or relational calculus, and that this...

by the creator of the relational database model, E. F. Codd, SQL null serves to fulfill the requirement that all true relational database management systems...

process relational data streams, the operators are equal or similar to the operators of the Relational algebra, so that there are operators for selection, projection...

structure of EAV data model is a perfect candidate for Relational Division, see relational algebra. With a good indexing strategy it's possible to get a...

domain if we allow the inverse to be a multivalued function. In relational algebra, a selection (sometimes called a restriction to avoid confusion with SQL's...

These consist of logical optimization—which generates a sequence of relational algebra to solve the query—and physical optimization—which is used to determine...

recognized to be an outgrowth of relational query optimization, where query evaluation programs were defined as relational algebra expressions, and query optimization...

relations are defined, it is possible to develop fuzzy relational databases. The first fuzzy relational database, FRDB, appeared in Maria Zemankova's dissertation...

development. Queries are parsed into domain-specific representations, like relational algebra for SQL, and optimized. The generated logical execution plans are...

a type of covalent bond in chemistry (sigma bond) the selection operator in relational algebra stress in mechanics electrical conductivity area density...

time to be inherently relational. Leibniz's 1690 discovery of his algebra of concepts (deductively equivalent to the Boolean algebra) and the associated...

type of conceptual schema or semantic data model of a system, often a relational database, and its requirements in a top-down fashion. Diagrams created...

methods such as hidden Markov models, Bayesian reasoning, and statistical relational learning. Symbolic machine learning addressed the knowledge acquisition...

approximation is a group of algorithms in multivariate analysis and linear algebra where a matrix V is factorized into (usually) two matrices W and H, with...

columns (which turns it into a candidate key). SQL allows the selection of rows from a relational table: this operation will in general yield a multiset, unless...