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Database Modeling & Design Fourth Edition- P51: Database technology has evolved rapidly in the three decades since the rise and eventual dominance of relational database systems. While many specialized database systems (object-oriented, spatial, multimedia, etc.) have found substantial user communities in the science and engineering fields, relational systems remain the dominant database technology for business enterprises. | Glossary 237 requirements specification A formal document that defines the requirements for a database in terms of the data needed the major users and their applications the physical platform and software system and any special constraints on performance security and data integrity. row A group of data items treated as a unit by an application a record a tuple in relational database terminology. schema A conceptual data model that shows all the relationships among the data elements under consideration in a given context the collection of table definitions in a relational database. second normal form 2NF A table is in second normal form 2NF if and only if each nonkey attribute data item is fully dependent on the primary key that is either the left side of every functional dependency FD is a primary key or can be derived from a primary key. star schema The basic form of data organization for a data warehouse consisting of a single large fact table and many smaller dimension tables. subtype entity The higher-level abstract entity in a generalization relationship. superkey A set of one or more attributes data items that taken collectively allows the unique identification of an entity or a record in a relational table. supertype entity The lower-level entity in a generalization relationship. table In a relational database the collection of rows or records of a single type similar to a file . ternary relationship A relationship that can only be defined among occurrences of three entities. third normal form 3NF A table is in third normal form 3NF if and only if for every functional dependency X- A where X and A are either simple or composite attributes data items either X must be a superkey or A must be a member attribute of a candidate key in that table. UML Unified Modeling Language a popular form of diagramming tools used to define data models and processing steps in a software application. 238 Glossary view integration A step in the logical design part of the database
