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MySQL, Check if a column exists in a table with SQL
... query that will check if a specific table in MySQL has a specific column, and if not — create it. Otherwise do nothing. This is really an easy procedure in any enterprise-class database, yet MySQL seems to be an exception.
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Delete an element from a dictionary
... del/assignment/etc. means you're going from constant time to linear time, and also using linear space. For small dicts, this is not a problem. But if you're planning to make lots of copies of large dicts, you probably want a different data structure, like a HAMT (as described in this answer).
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JavaScript private methods
... every object instance, it creates a separate function bound to the object and not the class. Also, this does not get garbage collected until the object itself is destroyed.
– Arindam
Feb 6 '12 at 22:37
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How to decide font color in white or black depending on background color?
...need to break the hex code into 3 pieces to get the individual red, green, and blue intensities. Each 2 digits of the code represent a value in hexadecimal (base-16) notation. I won't get into the details of the conversion here, they're easy to look up.
Once you have the intensities for the individ...
Significant new inventions in computing since 1980
...World Wide Web ("distributed hypertext via simple mechanisms") as proposed and implemented by Tim Berners-Lee started in 1989/90.
While the idea of hypertext had existed before (Nelson’s Xanadu had tried to implement a distributed scheme), the WWW was a new approach for implementing a distribute...
jQuery map vs. each
In jQuery, the map and each functions seem to do the same thing. Are there any practical differences between the two? When would you choose to use one instead of the other?
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Should I learn C before learning C++? [closed]
I visited a university CS department open day today and in the labs tour we sat down to play with a couple of final-year projects from undergraduate students. One was particularly good - a sort of FPS asteroids game. I decided to take a peek in the src directory to find it was done in C++ (most of...
Overflow-x:hidden doesn't prevent content from overflowing in mobile browsers
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Creating a site wrapper div inside the <body> and applying the overflow-x:hidden to the wrapper instead of the <body> or <html> fixed the issue.
It appears that browsers that parse the <meta name="viewport"> tag simply ignore overflow attributes on t...
Break promise chain and call a function based on the step in the chain where it is broken (rejected)
...et's say you have something like the following:
stepOne()
.then(stepTwo, handleErrorOne)
.then(stepThree, handleErrorTwo)
.then(null, handleErrorThree);
To better understand what's happening, let's pretend this is synchronous code with try/catch blocks:
try {
try {
try {
...
Best way to represent a fraction in Java?
...too long ago, for Project Euler problems. It keeps a BigInteger numerator and denominator, so it'll never overflow. But it'll be a tad slow for a lot of operations that you know will never overflow.. anyway, use it if you want it. I've been dying to show this off somehow. :)
Edit: Latest and gre...