数据依赖是一类数据约束,数据的语义解释决定了数据库中的数据应遵循的约束.数据库设计理论涉及一个基本问题——数据依赖的确定,实践中,对于数据依赖的确定,专业人员往往依赖实例数据的分析或者凭经验判断.为了探讨数据依赖的确定问题,通过实例数据分析发现数据依赖的方法,指出其不可靠,提出了通过语义分析确定数据依赖的思路,并对函数依赖、包含依赖、多值依赖和连接依赖的语义分析作了阐释.%Data dependencies is a class of data constraints,the semantic interpretation of the data determines the data in the database should follow the constraints.Database design theory involves a fundamental question-to determine the data dependent,in practice,for the determination of data dependencies,professionals often rely on instance data analysis or experience.In order to discuss the determination of data dependencies,we analysed methods that found data dependency through data instances,and pointed out they were not reliable.We put forward a semantic analysis way to determine the data dependency,and semantic analysis about functional dependency,including dependency,multivalued dependency and connection-dependency were presented.The research has theoretical reference value on database system design and management.
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