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Discovering SQL: A Hands-On Guide for Beginners by Alex Kriegel

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SESSIONS

Whatever happens in terms of communication between an RDBMS server and a user accessing it happens in the context of a session. Think of it as a unique channel open for you, and you only, to access the data; or in the case of desktop databases such as Microsoft Access and OpenOffice BASE, your very own copy of the data file. A session is created for you automatically when you connect to a database and get authenticated.

In a multiuser environment, one of the primary concerns is data integrity. When a client application establishes a connection to an RDBMS server, it is said to open a session. The session becomes this application's private communication channel. The user may change some preferences within the session (for example, default language or default date format); these settings would affect only this particular user environment and would remain valid for the duration of the session only. The details of the implementation and default behavior of the sessions might differ among the RDBMSs, but these basic principles remain the same.

The tools we used throughout the book are the examples of clients accessing RDBMS servers in context of a session. In the case of desktop databases, things are a bit different. Microsoft Access files, for instance, can be used as just data storage or can contain more objects normally associated with an application: forms, reports, and so on (and there are ways to split the functionality into front-end and back-end files). As such, the ...

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