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With a true short-circuiting conditional operator, person.Name is not evaluated unless person is not null. Visual Basic Version 9 has added the operator If() in addition to the existing IIf() function that existed previously. As a true operator, it does not have the side effects and potential inefficiencies of the IIf() function.
In object-oriented computer programming, a null object is an object with no referenced value or with defined neutral (null) behavior.The null object design pattern, which describes the uses of such objects and their behavior (or lack thereof), was first published as "Void Value" [1] and later in the Pattern Languages of Program Design book series as "Null Object".
Nullable types are a feature of some programming languages which allow a value to be set to the special value NULL instead of the usual possible values of the data type.In statically typed languages, a nullable type is an option type, [citation needed] while in dynamically typed languages (where values have types, but variables do not), equivalent behavior is provided by having a single null ...
In SQL, null or NULL is a special marker used to indicate that a data value does not exist in the database. Introduced by the creator of the relational database model, E. F. Codd , SQL null serves to fulfill the requirement that all true relational database management systems ( RDBMS ) support a representation of "missing information and ...
In database theory, a conjunctive query is a restricted form of first-order queries using the logical conjunction operator. Many first-order queries can be written as conjunctive queries. In particular, a large part of queries issued on relational databases can be expressed in this way.
If-then-else flow diagram A nested if–then–else flow diagram. In computer science, conditionals (that is, conditional statements, conditional expressions and conditional constructs) are programming language constructs that perform different computations or actions or return different values depending on the value of a Boolean expression, called a condition.
In computer science, a null function (or null operator) is a subroutine that leaves the program state unchanged. When it is part of the instruction set of a processor, it is called a NOP or NOOP (No OPeration). Mathematically, a (computer) function is null if and only if its execution leaves the program state unchanged.
Many languages have an operator to accomplish the same purpose, generally referred to as a conditional operator (or, less precisely, as a ternary operator); the best known is ?:, as used in C, C++, and related languages. Some of the problems with the IIf function, as discussed later, do not exist with a conditional operator, because the ...