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What are database normal forms and can you give examples? [closed]
...piece of information, and there can be no duplicate rows.
2NF and 3NF are all about being dependent on the primary key. Recall that a primary key can be made up of multiple columns. As Chris said in his response:
The data depends on the key [1NF], the whole key [2NF] and nothing but the key [3NF] ...
How can I randomize the lines in a file using standard tools on Red Hat Linux?
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I'm usually a Perl fan, but came across this ruby example which has the benefit of being shorter: ruby -e 'puts STDIN.readlines.shuffle'. It would need testing on big inputs to see if the speed is comparable. (also works on OS X)
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Unicode equivalents for \w and \b in Java regular expressions?
...cter class shorthand as "any letter, digit, or connecting punctuation" (usually: underscore). That way, a regex like \w+ matches words like hello , élève , GOÄ_432 or gefräßig .
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Why 0 is true but false is 1 in the shell?
The above will output 1 , which is contradictory with all other programming languages I know.
10 Answers
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Where can I learn how to write C code to speed up slow R functions? [closed]
...ds C++ and Rcpp to be much more like writing R than writing C++. YMMV and all that.
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npm install vs. update - what's the difference?
What is the practical difference between npm install and npm update ? When should I use which?
5 Answers
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What is the difference between C# and .NET?
.... The C# specification says only a very little about the environment (basically, that it should contain some types such as int, but that's more or less all).
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This Handler class should be static or leaks might occur: IncomingHandler
...e a reference to your Service object.
Handler objects for the same thread all share a common Looper object, which they post messages to and read from.
As messages contain target Handler, as long as there are messages with target handler in the message queue, the handler cannot be garbage collecte...
Why don't Java Generics support primitive types?
...nerics in Java are an entirely compile-time construct - the compiler turns all generic uses into casts to the right type. This is to maintain backwards compatibility with previous JVM runtimes.
This:
List<ClassA> list = new ArrayList<ClassA>();
list.add(new ClassA());
ClassA a = list.g...
Using a strategy pattern and a command pattern
...s encapsulate an algorithm and decouple implementation details from their calling classes. The only difference I can discern is that the Strategy pattern takes in parameters for execution, while the Command pattern doesn't.
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