SQL extended with transient fields for calculation expressions in enhanced data models

摘要

A database language (e.g. SQL) is extended to define a transient field whose value is derived from data stored in a database. The value of the transient field is calculated by the database engine for consumption as needed by the application layer, for example as part of a particular data model. The value of the transient field may not be materialized as a persistent field in the underlying database table, or may be selectively materialized based upon a heuristic or hint. Certain embodiments may implement the transient field as a basic elaboration on standard SQL utilizing an identifier. Some embodiments may implement the transient field as an entity where SQL has been extended to accommodate concepts of a higher-level Entity Relationship Model (ERM). The use of constants and/or floating values (e.g. a current time) in connection with transient fields, is also disclosed.