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SQL is null and = null [duplicate]
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In SQL, a comparison between a null value and any other value (including another null) using a comparison operator (eg =, !=, <, etc) will result in a null, which is considered as false for the purposes of a where clause (strictly speaking, it's "not true", rather...
How do I request a file but not save it with Wget? [closed]
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Use q flag for quiet mode, and tell wget to output to stdout with O- (uppercase o) and redirect to /dev/null to discard the output:
wget -qO- $url &> /dev/null
> redirects application output (to a file). if > is preceded by ampersand, sh...
How to exclude certain messages by TAG name using Android adb logcat?
Logcat allows filtering logs but it works like that: You define filters and logcat only displays messages which matches filters. But is there a way to display all logs EXCEPT some TAGs defined by filters?
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JavaScript, Node.js: is Array.forEach asynchronous?
...k at the specification of the algorithm.
However a maybe easier to understand implementation is given on MDN:
if (!Array.prototype.forEach)
{
Array.prototype.forEach = function(fun /*, thisp */)
{
"use strict";
if (this === void 0 || this === null)
throw new TypeError();
va...
How do I check for null values in JavaScript?
... !user){
Which will check for empty strings (""), null, undefined, false and the numbers 0 and NaN
Please note that if you are specifically checking for numbers it is a common mistake to miss 0 with this method, and num !== 0 is preferred (or num !== -1 or ~num (hacky code that also checks agains...
Selectively revert or checkout changes to a file in Git?
Is there a command that allows you to partially undo the changes to a file (or files) in the working directory?
4 Answers
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What exactly is a Context in Java? [duplicate]
I Googled this and read the Java documentation, but I'm a bit confused. Can somebody please explain what a Context is in plain English?
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How to turn on line numbers in IDLE?
...on 3.8 or newer:
To show line numbers in the current window, go to Options and click Show Line Numbers.
To show them automatically, go to Options > Configure IDLE > General and check the Show line numbers in new windows box.
Version 3.7 or older:
Unfortunately there is not an option to display...
How do I make a reference to a figure in markdown using pandoc?
I'm currently writing a document in markdown and I'd like to make a reference to an image from my text.
6 Answers
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Deleting lines from one file which are in another file
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This has O(n²) complexity and will start to take hours to complete once the files contain more than a few K lines.
– Arnaud Le Blanc
Jan 24 '11 at 10:59
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