外文翻譯---access2000關(guān)系型數(shù)據(jù)庫-數(shù)據(jù)庫-wenkub
2023-05-19 11:17:25 本頁面
【正文】 packet available at the same time facilitate the desktop database and a powerful relational database functions. In Access2020, with the user database access permissions are two types: Explicit and implicit powers authority. Explicit authority is granted a direct user account petence, which is the exclusive use of user accounts, has nothing to do with other users. Implicit authority is delegated the authority group account, the user added to the group was given by the group39。s mandate. If a user with the same time these two powers, the right set of user security database for a visit, then He had such authority is the intersection of the two powers. The Access20202020database, the group of users’ access to the database and the authority set up work, pleted only through the administrator. Set up the authority include: Open/Run, read design, design modifications, management, read data, update data insertion and deletion of data. Relational database management system inherent limitations in the following three aspects: Relational database used in the twodimensional table data model, can not effectively handle the majority of business applications, Typical of multidimensional data. Its inevitable result is that in plex ways, the interaction of the dramatic increase in the number of tables, not very good but also to provide realistic simulation of the data model. Relational database as they use more data model, which might lead to a massive storage space and wasting a lot of increase, and cause the system to respond to the declining performance. Furthermore, the data in reality, there are many types of relational database is not well addressed. Static applications such as report generation, and the design of the relational database management system after no response and efficient business processing for the optimization process. The result is often some relational database products, in the GUI and Web Services processing, not achieved the desired results. Unless additional hardware investment, but it does not resolve the fundamental problem. Relations with the twodimensional database table data model can deal with the majority of business application of a typical multi dimensional data, but the results are often the establishment and use of a large amount of data forms, it is difficult to establish a simulation of realworld data model. And the need for data output statements when they, in turn, would have dispersed the large number of twodimensional data tables. Reuse indexing technology linking the table in order to find all the necessary data, this, in turn, is bound to affect the use of the response speed. Database various databases
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