2019年2月16日 · 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 …

2012年3月6日 · 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 …

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 …

2011年4月14日 · 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 …

2012年2月5日 · In Java I am told that when doing a null check one should use == instead of .equals(). What are the reasons for this?

2021年9月21日 · 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 …

2010年7月20日 · How do I refer to the null object in Python?

2017年9月6日 · Comparing NULL with anything yields a NULL. NULL is part of trinary logic: TRUE, FALSE, and NULL. -- These are all NULL. select NULL > -1, NULL < -1, NULL = …

The title of this bug says "check for undefined or null", but the question itself checks for undeclared or null.

2015年1月23日 · There are many people who think that the concept of the special value null (as it is used in lanuages like C, Java, C#, Perl, Javascript, SQL etc.) is a bad idea. There are …