确实是,ORACLE,DB2,INFORMIX,MYSQL本质上都是关系型的,尽管提供了一些OO的功能,有兴趣的看看下面: Although there are different types of databases, such as sequential, hierarchical database, the commonly used types are relational, object-oriented and the object-relational database. Relational database management system (RDBMS), based on the relational model proposed by E.F.Cod 1970, organizes data into tables. Rows and columns of a table represent records and attributes. Relational databases use Structured Query Language (SQL) as the data definition language (DDL) and the data manipulation language (DML). The relational model has been adopted in products like ORACLE, DB2, INGRES, INFORMIX, SYBASE, etc. These products are characterized by a better physical/logical independence, greater flexibility, and specification languages. Object-oriented database management system (OODBMS) is built on the basis of The Object-Oriented Database System Manifesto [Atkinson 1989]. This manifesto was published by a group of researchers and has established the principles followed by OODBMS products like O2, ObjectStore, Objectivity, ITASCA, GemStone, SERVIO, etc. An object-oriented database employs a data model that supports object-oriented features such as encapsulation, inheritance and polymorphism. It utilizes the power of object-oriented programming languages to provide excellent database programming capability. A hybrid of RDBMS and OODBMS appeared recently called object-relational database management system (ORDBMS). The main objective of ORDBMS design was to benefit both the relational and the object models in scalability and support for rich data types. An ORDBMS employs a data model that attempts to incorporate OO features into RDBMSs. All database information is stored in tables, but some of the tabular entries may have richer data structure, termed abstract data types (ADTs). An ORDBMS supports an extended form of SQL called SQL3 in order to support ADT's. It has the relational model in it because the data is stored in the form of tables having rows and columns and SQL is used as the query language and the result of a query is also table or tuples (rows). Large RDBMS vendors such as ORACLE, IBM, Informix now are moving toward this direction. Their products are ORACLE 9i, DB2, Universal Server respectively.
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Rational Rose
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Rational Rose
erwin
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Although there are different types of databases, such as sequential, hierarchical database, the commonly used types are relational, object-oriented and the object-relational database.
Relational database management system (RDBMS), based on the relational model proposed by E.F.Cod 1970, organizes data into tables. Rows and columns of a table represent records and attributes. Relational databases use Structured Query Language (SQL) as the data definition language (DDL) and the data manipulation language (DML). The relational model has been adopted in products like ORACLE, DB2, INGRES, INFORMIX, SYBASE, etc. These products are characterized by a better physical/logical independence, greater flexibility, and specification languages.
Object-oriented database management system (OODBMS) is built on the basis of The Object-Oriented Database System Manifesto [Atkinson 1989]. This manifesto was published by a group of researchers and has established the principles followed by OODBMS products like O2, ObjectStore, Objectivity, ITASCA, GemStone, SERVIO, etc. An object-oriented database employs a data model that supports object-oriented features such as encapsulation, inheritance and polymorphism. It utilizes the power of object-oriented programming languages to provide excellent database programming capability.
A hybrid of RDBMS and OODBMS appeared recently called object-relational database management system (ORDBMS). The main objective of ORDBMS design was to benefit both the relational and the object models in scalability and support for rich data types. An ORDBMS employs a data model that attempts to incorporate OO features into RDBMSs. All database information is stored in tables, but some of the tabular entries may have richer data structure, termed abstract data types (ADTs). An ORDBMS supports an extended form of SQL called SQL3 in order to support ADT's. It has the relational model in it because the data is stored in the form of tables having rows and columns and SQL is used as the query language and the result of a query is also table or tuples (rows). Large RDBMS vendors such as ORACLE, IBM, Informix now are moving toward this direction. Their products are ORACLE 9i, DB2, Universal Server respectively.
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