Why does NULL = NULL evaluate to false in SQL server
Dec 4, 2009 · 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 …
SQL is null and = null - Stack Overflow
Mar 6, 2012 · 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 …
Java null check why use == instead of .equals() - Stack Overflow
In Java I am told that when doing a null check one should use == instead of .equals(). What are the reasons for this?
What's the difference between " = null" and " IS NULL"?
May 1, 2010 · 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 …
How do I check for null values in JavaScript? - Stack Overflow
And then == null does a perfect job, because it covers exactly those 2 values. (i.e. == null is equivalent to === null && === undefined) In exceptional cases you do want a clear distinction …
What is the difference between "is not null" and "!= null"?
Sep 21, 2021 · The only difference (besides the syntax) is, that the compiler guarantees that no user-overloaded operator is called when using is not null instead of != null (or is null instead of …
c# - Math operations with null - Stack Overflow
Sep 6, 2013 · The operators for Nullable<T> are so-called "lifted" operators]; the c# compiler takes the operators available for T and applies a set of pre-defined rules; for example, with +, …
What is the difference between NULL, '\0' and 0? - Stack Overflow
In C, there appear to be differences between various values of zero -- NULL, NUL and 0. I know that the ASCII character '0' evaluates to 48 or 0x30. The NULL pointer is usually defined as: …
How can I check for an undefined or null variable in JavaScript?
The title of this bug says "check for undefined or null", but the question itself checks for undeclared or null.
How do I create a unique constraint that also allows nulls?
Apr 20, 2009 · I want to have a unique constraint on a column which I am going to populate with GUIDs. However, my data contains null values for this columns. How do I create the constraint …