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How to UPSERT (MERGE, INSERT … ON DUPLICATE UPDATE) in PostgreSQL?
...o do an upsert, which is what MySQL calls INSERT ... ON DUPLICATE UPDATE and the standard supports as part of the MERGE operation.
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How can we programmatically detect which iOS version is device running on? [duplicate]
I want to check if the user is running the app on iOS less than 5.0 and display a label in the app.
10 Answers
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Is there a software-engineering methodology for functional programming? [closed]
...g as it is taught today is entirely focused on object-oriented programming and the 'natural' object-oriented view of the world. There is a detailed methodology that describes how to transform a domain model into a class model with several steps and a lot of (UML) artifacts like use-case-diagrams or ...
What is a build tool?
For past 4 years, I have been programming with Eclipse (for Java), and Visual Studio Express (for C#). The IDEs mentioned always seemed to provide every facility a programmer might ask for (related to programming, of course).
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Big O of JavaScript arrays
Arrays in JavaScript are very easy to modify by adding and removing items. It somewhat masks the fact that most languages arrays are fixed-size, and require complex operations to resize. It seems that JavaScript makes it easy to write poorly performing array code. This leads to the question:
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What is the difference between 127.0.0.1 and localhost
...hen (intelligent) software will just turn that directly into an IP address and use it. Some implementations of gethostbyname will detect the dotted format (and presumably the equivalent IPv6 format) and not do a lookup at all.
Otherwise, the name has to be resolved. And there's no guarantee that yo...
valueOf() vs. toString() in Javascript
In Javascript every object has a valueOf() and toString() method. I would have thought that the toString() method got invoked whenever a string conversion is called for, but apparently it is trumped by valueOf().
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What's the difference between “version number” in iTunes Connect, “bundle version”, “bundle version
... 12345AB). This is shown in the About window for Mac OS X apps for example and is often more a "Build Number" than a "Version Number".
Bundle Version String (CFBundleShortVersionString)
This value is used as the "real" version number. This must be the same string as used for the version in iTunes Co...
Hidden features of Perl?
...ation when looping through the records (usually lines) returned by a file handle, without using a flag variable:
while(<$fh>)
{
next if 1..1; # skip first record
...
}
Run perldoc perlop and search for "flip-flop" for more information and examples.
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Why is null an object and what's the difference between null and undefined?
...n short; undefined is where no notion of the thing exists; it has no type, and it's never been referenced before in that scope; null is where the thing is known to exist, but it's not known what the value is.
One thing to remember is that null is not, conceptually, the same as false or "" or such, e...