To be effective, it must be simple enough to communicate the required data structure to the end user, yet detailed enough that the database designer can create the physical structure.

为了是数据模型更加有效，它必须足够简单以使最终用户能够沟通必需的数据结构，同时它也要足够详细以使数据库设计人员能够创建物理结构。

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For example, a system designer is interested in the logical and physical aspects of a system, so the most useful forms are class and sequence diagrams rather than use-case and activity diagrams.

例如，系统设计人员对系统的逻辑和物理方面感兴趣，因此最有用的形式就是类和序列关系图，而不是用例和活动关系图。

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In most cases the designer can use a configuration that best fits the physical requirements of the system.

多数情况下由设计师根据系统的物理要求采用最适宜的配置。

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