好色
发表于 2025-3-23 12:20:53
More on Keys and Constraints,bles. In this chapter, we take another look at some of these ideas and think about some alternative possibilities. In particular, we take a closer look at primary keys and how to choose them. We also take a look at how we can maintain referential integrity when data is being constantly updated
用肘
发表于 2025-3-23 15:19:38
Other Implementations,e as a set of normalized tables related by foreign keys. The previous two chapters showed how we could efficiently enter data into these tables and use queries to extract meaningful information and reports
正论
发表于 2025-3-23 20:12:19
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Anticoagulants
发表于 2025-3-23 23:51:00
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祝贺
发表于 2025-3-24 05:00:37
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妈妈不开心
发表于 2025-3-24 06:39:14
Waldemar Cruz,Fanghui Liu,Laurent Micheled with two separate classes, for example Lecturers and Students, and then begin to realize that there is a great deal of information in common or that they are involved in the same relationships (who has parking permits, say). How do we handle these “same only different” cases in a pragmatic way?
羽毛长成
发表于 2025-3-24 13:55:08
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珠宝
发表于 2025-3-24 17:03:54
What Can Go Wrong,sarily the correct one. Often a table or spreadsheet is designed to mimic a possible data entry screen or a hoped-for report. This practice may be adequate for solving the immediate problem (e.g., storing the data somewhere); however, mimicking a data entry screen or report in your database design o
CAPE
发表于 2025-3-24 20:19:35
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沙文主义
发表于 2025-3-25 02:58:32
Learning from the Data Model,first attempt at determining the data that is necessary to support those tasks and formed an initial data model, which we depicted with a class diagram. In this chapter, we look more closely at the data model to see how it can further our understanding of a database system