DATABASE SYSTEMS (phần 21) potx

... types of distributed database systems, including federated and multidatabase systems and highlights the problems of heterogeneity and the needs of autonomy in federated database systems, which will ... retrieve the employee 25.7 Distributed Databases in Oracle I831 Net8 Database server Database server Net8 (c:::>c:::>c:::> = EMPtable t- , , Sales , database CONNECT T...

Ngày tải lên: 07/07/2014, 06:20

... (see Chapter 6). Practical Database Design and Tuning In this chapter, we first discuss the issues that arise in physical database design in Section 16.1. Then, we discuss how to improve database performance through database tuning in Section ... undertaking physical database design, we must have a good idea of the intended use of the database by defining the queries and transacti...

Ngày tải lên: 07/07/2014, 06:20

... in a database. Because part of the theoretical foundation for some deductive database systems is mathematical logic, such rules are often referred to as logic databases. Other types of systems, ... in the application programs that access the database. Section 24.3 will give a brief overview of spatial and multimedia databases. Spatial databases provide concepts for databases that kee...

Ngày tải lên: 07/07/2014, 06:20

... using, and imple- menting database systems and applications. Our presentations stresses the fundamentals of database modeling and design, the languages and facilities provided by the database management systems, and system implementation techniques. The book is meant to be used ... I Chapter 1 Databases and Database Users DATABASE SYSTEM UserS/Programmers ~ Application Programs/...

Ngày tải lên: 07/07/2014, 06:20

... are becoming quite popular. These systems provide an environment for developing database applications and include facilities that help in many facets of database systems, including database design, CUI development, querying and ... processing and optimization, their performance improved. Eventually, relational databases became the dominant type of database systems for traditiona...

Ngày tải lên: 07/07/2014, 06:20

... additional facts from the facts stored in a database. Hence, whereas most current database systems are limited to answering direct queries, knowledge-based systems using KR schemes can answer queries that involve inferences over the stored ... relational database and a rela- tional database schema. A relational database schema S is a set of relation schemas S = (R I , R z , ,...

Ngày tải lên: 07/07/2014, 06:20

... as RM/T. Childs (1968) had earlier used set theory to model databases. Later, Codd (1990) published a book examining over 300 features of the relational data model and database systems. Since Codd's pioneering ... discuss JOIN and other complex binary operations, which operate on two tables. The COMPANY relational database shown in Figure 5.6 is used for our examples. Some common...

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...

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... appropriate SQL DDL statements to define the database. 8.8. Repeat Exercise 8.7, but use the AIRLINE database schema of Figure 5.8. 8.9. Consider the LIBRARY relational database schema of Figure 6.12. Choose the appro- priate action (reject, ... updating, and the specification of views. Most database systems have an interactive interface where these SQL commands can be typed directl...

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... 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 ... and EMP _PROJI. 9.5 Database Programming with Function Calls: SQL/CLI and JDBC I 277 records, represented as structs in C data types. An environment...

Ngày tải lên: 07/07/2014, 06:20