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Difference between Key, Primary Key, Unique Key and Index in MySQL
...would use indexes to improve the speed of data retrieval. An index is typically created on columns used in JOIN, WHERE, and ORDER BY clauses.
Imagine you have a table called users and you want to search for all the users which have the last name 'Smith'. Without an index, the database would have t...
How to impose maxlength on textArea in HTML using JavaScript
...
@JoshStodola - Indeed you cannot. It would really annoy me as a user if I had pasted a whole piece of something in a textarea, clicked submit, and only saw a small portion of it go through without any response.
– Travis J
Apr 30 '1...
PATH issue with pytest 'ImportError: No module named YadaYadaYada'
I used easy_install to install pytest on a mac and started writing tests for a project with a file structure likes so:
20 A...
isset() and empty() - what to use
... check - is variable empty or contains something. To solve this task, I usually do the following.
6 Answers
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Working with time DURATION, not time of day
... cell B2 and drag as far down as the A column goes to apply the formula to all data in col A.
Last step, be sure to highlight all of column B and set it to Number format (the application of the formula may have automatically set format to Time).
...
moving changed files to another branch for check-in
... you have not made the commit yet, just run git stash. This will save away all of your changes.
Switch to the branch you want the changes on and run git stash pop.
There are lots of uses for git stash. This is certainly one of the more useful reasons.
An example:
# work on some code
git stash
gi...
What is the difference between Polymer elements and AngularJS directives?
...js is a library that contains several polyfills for various W3C APIs that fall under the Web Components umbrella. These are:
Custom Elements
HTML Imports
<template>
Shadow DOM
Pointer Events
others
The left-nav in the documentation (polymer-project.org) has a page for all of these "Platfor...
What's the difference between utf8_general_ci and utf8_unicode_ci?
...languages or characters.
On modern servers, this performance boost will be all but negligible. It was devised in a time when servers had a tiny fraction of the CPU performance of today's computers.
Benefits of utf8mb4_unicode_ci over utf8mb4_general_ci
utf8mb4_unicode_ci, which uses the Unicode r...
What is the most frequent concurrency issue you've encountered in Java? [closed]
...are not synchronized this is not guaranteed to work. This mistake is especially devilish as in 99.999% it won't matter in practice as the reader thread will eventually see the change - but we don't know how soon he saw it.
s...
Use of .apply() with 'new' operator. Is this possible?
...CMAScript5's Function.prototype.bind things get pretty clean:
function newCall(Cls) {
return new (Function.prototype.bind.apply(Cls, arguments));
// or even
// return new (Cls.bind.apply(Cls, arguments));
// if you know that Cls.bind has not been overwritten
}
It can be used as foll...