A DBMS is a complex software system. In this section we discuss the types of software components that constitute a DBMS and the types of computer database system software with which the DBMS interacts. DBMS Component Modules Figure illustrates, in a simplified form, the typical DBMS components. The figure is divided into two parts. The
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Already we discussed the variety of users supported by a DBMS. The DBMS must provide appropriate languages and interfaces for each category of users. In this section we discuss the types of database languages and interfaces provided by a DBMS and the user categories targeted by each interface. DBMS Languages Once the design of a
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Three of the four important characteristics of the database approach, listed in Section, are (1) use of a catalog to store the database description (schema) so as to make it self describing, (2) insulation of programs and data (program data and program operation independence), and (3) support of multiple user views. In this section we
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One fundamental characteristic of the database approach is that it provides some level of data abstraction. Data abstraction generally refers to the suppression of details of data organization and storage, and the highlighting of the essential features for an improved understanding of data. One of the main characteristics of the database approach is to support
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In spite of the advantages of using a DBMS, there are a few situations in which a DBMS may involve unnecessary overhead costs that would not be incurred in traditional file processing. The overhead costs of using a DBMS are due to the following: High initial investment in hardware, software, and training The generality that
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We now give a brief historical overview of the applications that use DBMSs and how these applications provided the impetus for new types of database systems. Early Database Applications Using Hierarchical and Network Systems Many early database applications maintained records in large organizations such as corporations, universities, hospitals, and banks. In many of these applications,
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In this section we discuss some of the advantages of using a DBMS and the capabilities that a good DBMS should possess. These capabilities are in addition to the four main characteristics discussed in Section. The DBA must utilize these capabilities to accomplish a variety of objectives related to the design, administration, and use of
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In addition to those who design, use, and administer a database, others are associated with the design, development, and operation of the DBMS software and system environment. These persons are typically not interested in the database content itself. We call them the workers behind the scene, and they include the following categories: DBMS system designers
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For a small personal database, such as the list of addresses discussed in Section, one person typically defines, constructs, and manipulates the database, and there is no sharing. However, in large organizations, many people are involved in the design, use, and maintenance of a large database with hundreds of users. In this section we identify
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A number of characteristics distinguish the database approach from the much older approach of programming with files. In traditional file processing, each user defines and implements the files needed for a specific software application as part of programming the application. For example, one user, the grade reporting office, may keep files on students and their
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