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In contrast to the Visual Basic function by this name, it does not return a Boolean, but instead returns the first expression if that is not NULL, otherwise the second expression. [22] The purpose of the function is to replace any NULL values with another, presumably (but not required to be) non- NULL , value. [ 23 ]
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.
The null coalescing operator is a binary operator that is part of the syntax for a basic conditional expression in several programming languages, such as (in alphabetical order): C# [1] since version 2.0, [2] Dart [3] since version 1.12.0, [4] PHP since version 7.0.0, [5] Perl since version 5.10 as logical defined-or, [6] PowerShell since 7.0.0, [7] and Swift [8] as nil-coalescing operator.
Additionally, because SQL operators return Unknown when comparing anything with Null directly, SQL provides two Null-specific comparison predicates: IS NULL and IS NOT NULL test whether data is or is not Null. [8] SQL does not explicitly support universal quantification, and must work it out as a negated existential quantification.
In computing, IIf (an abbreviation for Immediate if [1]) is a function in several editions of the Visual Basic programming language and ColdFusion Markup Language (CFML), and on spreadsheets that returns the second or third parameter based on the evaluation of the first parameter.
Visual Basic is not case sensitive, which means that any combinations of upper and lower case letters in keywords are acceptable. Visual Studio automatically converts all Visual Basic keywords to the default capitalised forms, e.g. "Public", "If". C# is case sensitive and all C# keywords are in lower cases.
The IS NULL and IS NOT NULL predicates (which use a postfix syntax) test whether data is, or is not, Null. [12] The SQL standard contains the optional feature F571 "Truth value tests" that introduces three additional logical unary operators (six in fact, if we count their negation, which is part of their syntax), also using postfix notation.
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 ...