This paper deals with the semantics of null values in functional dependencies in database theory, and presents three different definitions of FDs in a single relation with marked nulls.

本文研究关系数据库理论中空值在函数依赖中的语义问题，提出了带标志空值的关系中函数依赖的三种定义。

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In theory, date could be matched against a database kept by the drugmaker.

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If this second theory wins the day, Pfizer will be in the position of trying to use its vast database of Celebrex data to prove that Celebrex is a very special case.

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