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Data Models: Relational Database Model Review
Автор: Thomas Blum
Загружено: 2024-09-23
Просмотров: 35
Описание:
In this video we continue our discussion of data models. We mainly use it as a place to view much of the terminology developed earlier. The concept of a relation can be realized as a two-dimensional table in which we do not care about the order of the columns or the order of the rows. The columns are more a property of the schema (meta-data), and their count is known as the degree. The rows are more a property of the instance (data), and their count is the cardinality. We also discussed domains, validation rules, masks, and so on. We ended with a mention of keys: candidate, primary, and foreign.
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