A unified treatment of null values using constraints
نویسندگان
چکیده
منابع مشابه
A Unified Treatment of Null Values Using Constraints
An important reality when studying relational databases is the fact that entries in relational tables may often be \missing" or only partially speciied. The study of such missing information has led to a rich body of work on \null values." It was recognized early on that there are many diierent types of null values, each of which reeects diierent intuitions about why a particular piece of infor...
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ژورنال
عنوان ژورنال: Information Sciences
سال: 1997
ISSN: 0020-0255
DOI: 10.1016/s0020-0255(96)00201-0