服务承诺
资金托管
原创保证
实力保障
24小时客服
使命必达
51Due提供Essay,Paper,Report,Assignment等学科作业的代写与辅导,同时涵盖Personal Statement,转学申请等留学文书代写。
51Due将让你达成学业目标
51Due将让你达成学业目标
51Due将让你达成学业目标
51Due将让你达成学业目标私人订制你的未来职场 世界名企,高端行业岗位等 在新的起点上实现更高水平的发展
积累工作经验
多元化文化交流
专业实操技能
建立人际资源圈Database
2013-11-13 来源: 类别: 更多范文
Database
Relational database model versus Object Oriented database model.
The defining characteristic of a database is (arguably) the data model that it implements. A data model is an abstract, logical definition of the objects used to model the structure of data and the operators used to model its behavior.
The most popular type of DBMS - and the only type that is as widely used today are the relational database systems, based on the relational data model.
Relational systems:
Relational systems dominate the DBMS marketplace. Briefly (and loosely), a relational system is one in which:
1. The data is perceived by the user as tables (and nothing but tables); and
2. The operators available to the user (e.g. for retrieval) are operators
that generate new tables from old.
The term relation is basically just a mathematical term for a table.
Examples: Oracle, DB2 (IBM), Ingres (pr. ingress), Informix, SQL Server (Microsoft), Sybase, MySQL and PostgreSQL.
More often than not, database designers are concerned with designing, implementing and querying databases that use a relational model. Therefore, the relational database model is likely
systems, database, relational, data, object, model, dbms, operators, user, tables, one, objects, object-oriented, methods, classes, widely, views, types, type, term, system, structure, pre-relational, particular, oriented, oracle, object/relational, must, multi-dimensional, key, databases, complex, class, based, application

