Abstract. NULL is a special marker used in SQL to indicate that a value for an attribute of an object does not exist in the database.
NULL is a special marker used in SQL to indicate that a value for an attribute of an object does not exist in the database. Its aim is a representation of ...
This paper aims in developing a general approach to NULL 'values' and shows how they can be used without changing database technology. NULL is a special ...
NULL is a special marker used in SQL to indicate that a value for an attribute of an object does not exist in the database. Its aim is a representation of ...
In this paper, extension of the EQ-logic by the ∆-connective is introduced. The former is a new kind of many-valued logic which based on EQ-algebra of truth ...
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We show that, according to Codd's. Relational Model, a SQL null value represents a non-existing value; as a consequence no indeterminacy is introduced by SQL ...
We extend Codd's theorem by proving the equivalence of the relational algebra with both domain relational calculi in presence of SQL null values.
The logic of nulls in databases has been subject of investigation since their introduction in Codd's Relational Model, which is the foundation of the SQL ...
When. V is empty we write 1 for the unique conjunction of literals, namely the empty conjunction. We first derive the following useful identities from the ...
Dec 9, 2013 · Null is not a value. Ergo it is not part of the relational model of data. Ergo Relational Algebra (if it pretends to be truly relational) cannot and does not ...