A relation schema R(A 1,…, A n) describes a relation R of degree n by enumerating the n-attributes A 1,…, A n that characterize R. An attribute names a role played by some domain D in describing the entity modeled by R .

A relational schema (or relational database schema) is a set of relational table definitions, constraints, and perhaps derivation rules. You may wish to review Sections 1.3 and 2.3, where the basic ideas were discussed. The structure of a single relational table is called a table scheme or relation variable.

2022年2月1日 · Assuming a design with a “universal” relation (Fig. 2 c), the query evaluation over the relational schema (see Section 5 for the details on the SPARQL-to-SQL query evaluation) would require one self-join for each one of the w o r k s F o r, s u p e r v i s e s and i s M a r r i e d T o query conditions (h a s B i r t h d a y and h a s N a t ...

2019年9月1日 · In particular, the downward closure property means that the fewer tuples we consider in a relation the more FDs will satisfy that relation, which illustrates a trade-off between data losslessness (fewer tuples) and data integrity (more FDs that apply). This has two important consequences for the schema design of applications.

2020年2月1日 · A valid O-P case means that the point can be inspected by that probe orientation. A valid O-P relation schema includes all valid O-P cases. The validity of an O-P case is judged by two accessibility criteria which are detailed in Section 2.1, and the detailed algorithm to construct a valid O-P relation schema is given in Section 2.2.

2019年9月1日 · We then define a relation schema with p-degree scale α 1 > ⋯ > α k + 1 to be in α i-Key-based Insertion Anomaly Normal Form/Key-based Type-1/2/3 Modification Anomaly Normal Form(KIANF/KMANF-1/2/3) with respect to a given set of pFDs if and only if there is no p-relation over the schema that satisfies all given pFDs and in which a ...

1990年1月1日 · In this paper we discuss extensions to the conventional relational algebra to support both aspects of transaction time, evolution of a database's contents and evolution of a database's schema. We define a relation's schema to be the relation's temporal signature, a function mapping the relation's attribute names onto their value domains and ...

2003年5月1日 · Further conditions on a database schema in SSNF are that the hierarchical structure of the join tree induces its integrity constraints in terms of functional dependencies (FDs) and a restricted class of inclusion dependencies (INDs). Finally, the root of the join tree, whose relation schema corresponds to the fact table, must be in BCNF.

One theory that adequately addresses relational cognition, affect, and behaviour is Relational Schema Theory (RST; Baldwin, 1992). Relational schemas incorporate knowledge about both the self and the other, the self-in-relation-to-other, and expectations about interpersonal behaviour.

2003年4月15日 · The author claims that the universe of data to be modeled can be represented by one relation in a relational schema. Any relation in the database is a projection of a universe relation. Ref. [14] presents techniques for converting relational databases into object-oriented databases. The data conversion involves unloading tuples of relations ...