DATABASE SYSTEMS (phần 8) doc

... a constraint between two sets of attributes from the database. Suppose that our relational database schema has n attributes AI' A 2 , ••• , An; let us think of the whole database as being described by a single universal relation ... { 6) System.out.println ("Driver could not be loaded") ; 7) } 8) String dbacct, passwrd, ssn, lname 9) Double salary ; 10) dbacct = readent...

Ngày tải lên: 07/07/2014, 06:20

... databases and Web pages. XML combines concepts from the models used in document systems with database modeling concepts. 1.7.5 Extending Database Capabilities for New Applications The success of database systems in traditional applications ... processing and optimization, their performance improved. Eventually, relational databases became the dominant type of database systems fo...

Ngày tải lên: 07/07/2014, 06:20

... success of rela- tional databases in the commercial world. Because it became a standard for relational databases, users were less concerned about migrating their database applications from other types of database systems- for example, network or ... 10 b 5 FIGURE 6.13 A database state for the relations T1 and T2. Relational Database Design by ER- and EER-to-Relational Mapping We now...

Ngày tải lên: 07/07/2014, 06:20

... Context for Using Database Systems Database systems have become a part of the information systems of many organizations. In the 1960s information systems were dominated by file systems, but since ... THE DATABASE DESIGN AND IMPLEMENTATION PROCESS We now focus on activities 2 and 3 of the database application system life cycle, which are database design and implementation. T...

Ngày tải lên: 07/07/2014, 06:20

... Gray (19 78) discusses recov- ery, along with other system aspects of implementing operating systems for databases. The shadow paging technique is discussed in Lorie (1977), Verhofstad (19 78), and Reuter (1980). Gray et ... Object Databases 20.4 TYPE AND CLASS HIERARCHIES AND INHERITANCE Another main characteristic of 00 database systems is that they allow type hierarchies and inheri...

Ngày tải lên: 07/07/2014, 06:20

... relational database and an object database? 21.12. Describe the steps of the algorithm for object database design by EER-to-OO mapping. Exercises 21.13. Design an 00 schema for a database application that you ... discuss the concept of a database. Because a ODBMS can create many different databases, each with its own schema, the ODMG object model has interfaces for DatabaseFactory an...

Ngày tải lên: 07/07/2014, 06:20

... object. For manipulation of doc objects, functions such as the following are used: Import _doc (doc, text) returns doc. Export _doc (doc, text) returns text. Assign (doc) returns doc. Destroy (doc) returns void. The Assign and Destroy functions ... operation. Database audits are particularly important for sensitive databases thar are updated by many transactions and users, suc...

Ngày tải lên: 07/07/2014, 06:20

... OLAP 28.1 INTRODUCTION, DEFINITIONS, AND TERMINOLOGY In Chapter 1 we defined database as a collection of related data and a database system as a database and database software together. A data warehouse is also a ... of the software problems-which may involve data management, transaction management, and database recovery-have their origins in distributed database systems. In mob...

Ngày tải lên: 07/07/2014, 06:20

... http://www.ncbLnlm.nih.gov/genome/seq/. The MITOMAP database developed in Kogelnik (19 98) can be accessed at http://www.mitomap.org/. The biggest protein database SWISS-PROT can be accessed from http://expasy.hcuge.ch/sprot/. The ACEDB database information is available at http://probe.nalusda.gov:8080/acedocs/. 922 IChapter 29 Emerging Database Technologies and Applications Databas...

Ngày tải lên: 07/07/2014, 06:20

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