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ESQL2 - Extending SQL2 to Support Object-oriented and Deductive Databases

Institut National de Recherche en Informatique et en AutomatiqueGeorges GardarinPatrick Valduriez

出版	Institut National de Recherche en Informatique et en Automatique, 1992
URL	http://books.google.com.hk/books?id=Z4dLGwAACAAJ&hl=&source=gbs_api

註釋Abstract: "ESQL2 is an SQL2 upward-compatible database language that integrates in a uniform and clean way the essential concepts of relational, object-oriented and deductive databases. ESQL2 is intented [sic] for traditional data processing applications as well as more complex applications such as large expert systems. Therefore, ESQL's salient features are: a rich and extendible type system based on abstract data types (ADTs) which can be implemented in various programming languages; complex objects with object sharing by combining generic ADTs and object identity; the capability of querying and updating relations of values or classes of objects using extended SQL syntax and semantics; a DATALOG-like deductive capability provided as an extension of the SQL view mechanism; and control statements for programming stored procedures and multi- statement queries. As ESQL2 is a rich language, a graphical representation of ESQL2 database schemas and queries is proposed to simplify query formulation. A database is represented using extended entity-relationship diagrams. A query is pictured as a database view where only relevent [sic] parts of diagrams are used; in addition, types may be constrained by predicates. This representation yields an algorithm to translate ESQL2 queries in DATALOG extended with object identifiers, functions and sets, thereby defining the semantics of ESQL2 queries. Thus, ESQL2 may be perceived as a SQL-compatible syntax for expressing extended DATALOG queries."