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The Is functions (also known as data information functions, [5] data inspection functions, [6] or data-testing functions [6]) are a set of functions in Microsoft's Visual Basic 6, Visual Basic for Applications, VBScript, and Visual Basic .NET. Several of them are also provided in Transact-SQL by the .NET Framework Data Provider for Microsoft ...
In the above example, IIf is a ternary function, but not a ternary operator. As a function, the values of all three portions are evaluated before the function call occurs. This imposed limitations, and in Visual Basic .Net 9.0, released with Visual Studio 2008, an actual conditional operator was introduced, using the If keyword instead of IIf ...
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 ...
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.
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.
In addition to basic equality and inequality conditions, SQL allows for more complex conditional logic through constructs such as CASE, COALESCE, and NULLIF. The CASE expression, for example, enables SQL to perform conditional branching within queries, providing a mechanism to return different values based on evaluated conditions. This logic ...
The Contains operator checks, if the collection contains a given element. Count The Count operator counts the number of elements in the given collection. An overload taking a predicate, counts the number of elements matching the predicate. The standard query operator API also specifies certain operators that convert a collection into another ...
In these languages, the typeof operator is the method for obtaining run-time type information. In other languages, such as C# [2] or D [3] and, to some degree, in C (as part of nonstandard extensions and proposed standard revisions), [4] [5] the typeof operator returns the static type of the operand. That is, it evaluates to the declared type ...