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difference between primary key and unique key
...ultiple columns, e.g. Primary key (CustomerID, ProductID). This is called composite primary key. This is to clarify the first point, as it might be take as it is (read one key => one column ) by new comer to sql : )
– ken
Apr 10 '14 at 13:53
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Can you build dynamic libraries for iOS and load them at runtime?
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Anybody know why that is? To me it just seems completely insane.
– Erik de Castro Lopo
Apr 29 '11 at 3:24
74
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What is the difference between char * const and const char *?
...ld declare both variables to be int * const; I don't know any way to use a combined declaration to create two variables of that type without a typedef.
– supercat
Apr 12 '13 at 21:57
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What does template mean?
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unsigned int x = N;
In fact, we can create algorithms which evaluate at compile time (from Wikipedia):
template <int N>
struct Factorial
{
enum { value = N * Factorial<N - 1>::value };
};
template <>
struct Factorial<0>
{
enum { value = 1 };
};
// Factorial&l...
Dump a mysql database to a plaintext (CSV) backup from the command line
...s to mysqldump, I'm all ears. Also, I'd like something I can run from the command line (linux). If that's a mysql script, pointers to how to make such a thing would be helpful.
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How can the Euclidean distance be calculated with NumPy?
...found here: docs.scipy.org/doc/numpy/reference/generated/… My only real comment was sort of pointing out the connection between a norm (in this case the Frobenius norm/2-norm which is the default for norm function) and a metric (in this case Euclidean distance).
– Mark Lavin...
How to write a cron that will run a script every day at midnight?
...s--and the *s mean every day of every month.)
Syntax:
mm hh dd mt wd command
mm minute 0-59
hh hour 0-23
dd day of month 1-31
mt month 1-12
wd day of week 0-7 (Sunday = 0 or 7)
command: what you want to run
all numeric values can be replaced by * which means all
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What happens if you static_cast invalid value to enum class?
... CWG 1766 is considered a defect in the Standard, hence it is accepted for compiler implementers to apply to to their C++11 and C++14 compilation modes.
(*) char is required to be at least 8 bit wide, but isn't required to be unsigned. The maximum value storable is required to be at least 127 per A...
Git Clone: Just the files, please?
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The git command that would be the closest from what you are looking for would by git archive.
See backing up project which uses git: it will include in an archive all files (including submodules if you are using the git-archive-all s...