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c# - What does null! statement mean? - Stack Overflow It can be used on a type to control Nullability, it is then called the "Null Forgiving Operator" Basically, null! applies the ! operator to the value null This overrides the nullability of the value null to non-nullable, telling the compiler that null is a "non-null" type
SQL is null and = null - Stack Overflow The reasoning is that a null means "unknown", so the result of any comparison to a null is also "unknown" So you'll get no hit on rows by coding where my_column = null SQL provides the special syntax for testing if a column is null, via is null and is not null, which is a special condition to test for a null (or not a null)
What is the purpose of null? - Stack Overflow Null: The Billion Dollar Mistake Tony Hoare: I call it my billion-dollar mistake It was the invention of the null reference in 1965 At that time, I was designing the first comprehensive type system for references in an object oriented language (ALGOL W) My goal was to ensure that all use of references should be absolutely safe, with checking performed automatically by the compiler But I
javascript - Why is null an object and whats the difference between . . . In order to be able to query this difference, JavaScript has null and undefined: While null is - just like in other languages an object, undefined cannot be an object because there is no instance (even not a null instance) available
sql - Not equal lt; gt; != operator on NULL - Stack Overflow 135 NULL has no value, and so cannot be compared using the scalar value operators In other words, no value can ever be equal to (or not equal to) NULL because NULL has no value Hence, SQL has special IS NULL and IS NOT NULL predicates for dealing with NULL
Why does NULL = NULL evaluate to false in SQL server The expression "NULL = NULL" evaluates to NULL, but is actually invalid in SQL; yet ORDER BY treats NULLs as equal (whatever they precede or follow "regular" values is left to DBMS vendor)
What is null in Java? - Stack Overflow The null reference can always be cast to any reference type In practice, the programmer can ignore the null type and just pretend that null is merely a special literal that can be of any reference type What is null? As the JLS quote above says, in practice you can simply pretend that it's "merely a special literal that can be of any reference
Whats the difference between = null and IS NULL? Understanding the difference between “IS NULL” and “= NULL” When a variable is created in SQL with the declare statement it is created with no data and stored in the variable table (vtable) inside SQLs memory space The vtable contains the name and memory address of the variable
What is the difference between is not null and != null? The main difference between e != null and e is not null is the way the the compiler executes the comparison Microsoft: "The compiler guarantees that no user-overloaded equality operator == is invoked when expression x is null is evaluated " Bottom Line: If you are writing code that you don't want to depend on someone's implementation of the != and == operators, use is null and is not null