Subtyping : conceptual and logical issues
نویسندگان
چکیده
Subtyping is an important feature of semantic approaches to conceptual schema design and, more recently, object-oriented database design. However the relational model does not directly support subtyping, and CASE tools for mapping conceptual to relational schemas typically provide only very weak support for mapping subtypes. This paper surveys some of the main issues related to conceptual specification and relational mapping of subtypes, and indicates how Object-Role Modeling solves the associated problems.
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