In this paper, we first give conditions under which we can construct a universal instance I which uses only one type of nulls (unmarked nulls) and whose total ...
Representative instances are important since in addition to the uni- versal relation view they permit updates in the individual relations; if.
In this paper, we first give conditions under which we can construct a universal instance I which uses only one type of nulls (unmarked nulls) and whose total ...
Universal and Representative Instances Using Unmarked Nulls. ... S. Jajodia. FSTTCS, volume 181 of Lecture Notes in Computer Science, page 367-378.
A class of relation schemes for which no constraint is necessary is characterized, and we show how to compute projections of the representative instance for ...
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If R is γ-acyclic and r satisfies all existence constraints, then it is possible to construct a universal instance L, using unmarked nulls, whose total ...
An Extension of "Representative Instances and ?-Acyclic Relational ...
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Moreover, conditions were given which guarantee that this L would satisfy the functional dependency with nulls (NFD) counterparts of FD's, in F. The purpose of ...
NONAPPLICABLE NULLS - Nadine LERAT and Witold LIPSKI, Jr.
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Abstract. A nonapplicable null appears in a relation whenever the value of the corresponding attribute does not exist. In order to evaluate a query on a ...
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Our goal is to collect and analyze the shortcomings of nulls and their treatment by SQL, and to re-evaluate existing research in this light. To this end, we ...
Oct 7, 2015 · My list has 13 elements, 11 of which are NULL. I would like to remove them, but preserve the indices of the elements that are nonempty.