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ASP.NET PDF Viewer using C#, VB/NETPackages, procedures, functions, and triggers could all include transactions marked as autonomous. You have to include a directive in the main transaction so that Oracle will know you intend to use an autonomous transaction within the main transaction. The autonomous transaction can have its own ROLLBACK and COMMIT statements, just like normal transactions. The main transaction, by using an autonomous transaction, can pause and execute the autonomous transaction, and then continue from where it stopped. In other words, you leave the calling transaction s context, execute SQL statements that are part of the autonomous transaction, either commit or roll back your transaction, and resume the parent transaction upon returning to the calling transaction s context. Note that the autonomous transaction does not share transaction resources, such as locks, with the parent transaction. Autonomous transactions provide developers with the ability to create more fine-grained transactions, where a transaction will not be an all-or-nothing affair. You can have the nested autonomous transactions commit or roll back their transactions independent of the calling parent transaction. barcode generator excel 2016, excel barcodes free, how to activate barcode in excel 2010, free excel ean barcode font, insert barcode in excel 2016, barcode add in excel free, barcode generator for excel free download, excel barcode add in free download, how to insert barcode in excel 2010, excel vba barcode generator,Before you can proceed to actually create databases, you need to conceptually model the organization s information system so you can easily see the interrelationships among the various components of the system. Data models are simple representations of complex real-world data structures, and the models help you depict not only the data structures, but also the relationships among the components and any constraints that exist. Conceptual modeling of the enterprise leads to clear indications regarding the tables to be built later on and the relationships that should exist among those tables. ER modeling involves the creation of valid models of the business, using standard entity-relationship diagrams (ERDs). Note that the conceptual model is always independent of both software and hardware considerations. ER modeling was originally proposed by Peter Chen in 1976, and it is now the most widely used technique for database design. (You can download Chen s original proposal document as a PDF file at http://bit.csc.lsu.edu/~chen/pdf/erd.pdf.) Nevertheless, there are several design methodologies other than ER modeling available for you to use. For several years, researchers have struggled to model the real world more realistically by using semantic data models, which try to go beyond the traditional ER modeling methodology. The World Wide Web Consortium (W3C) is working on a specification related to data representation on the Internet. The general idea is to try to bring some meaning to the massive amount of data and information available. Information on the Web is designed for and presented to humans, but on the semantic Web, data and information will be designed so that it can be understood and manipulated by computers as well as humans. On the semantic Web, you will use software agents to go off in search of data and information on your behalf. An excellent article on this new and exciting approach is The Semantic Web, by Tim Berners-Lee, James Hendler, and Ora Lassila, available at http://www.scientificamerican.com/article.cfm articleID=00048144-10D21C70-84A9809EC588EF21&catID=2. ome environments do not use a shadow file for maintaining passwords. These environments keep encrypted passwords in either a local passwd file or one that is handled through NIS. I have seen this mode of operation in several versions of HP-UX and NIS. NIS can support using a shadow file, but not all NIS clients have this capability. The script in this chapter, which is intended to be run daily, creates and maintains a pseudo shadow file to track the age of user passwords and their change history. The script does not, however, remove the encrypted password from the already-existing passwd file. I intend this contrived shadow-file generator to be run in conjunction with the passwordaging script in 36. The script in that chapter relies on information contained in a shadow file to determine the date of the last password change. The first section of the script sets up several environment variables to be used later. The variables originally were taken from a separate configuration file, but for the sake of simplicity I have included them at the beginning of the script.
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