A database system is an overall collection of different database software components and databases containing the following parts:
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A database application program is special-purpose software that is designed and implemented by users or implemented by third-party software companies. In contrast,
client components are general-purpose database software designed and implemented by a database company. By using client components, users can access data stored on the
same or a remote computer.
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The task of a database server is to manage data stored in a database. Each client communicates with a database server by sending user queries to it. The server processes each query and sends the result back to the client.
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In general, a database can be viewed from two perspectives, the users’ and the database system’s. Users view a database as a collection of data that logically belong together.
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For a database system, a database is simply a series of bytes, usually stored on a disk. Although these two views of a database are totally different, they do have something in common: the database system needs to provide not only interfaces that enable users to create databases and retrieve or modify data, but also system components to manage the stored data. Hence, a database system must provide the following features:
