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What are database normal forms and can you give examples? [closed]
...ontain only one 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 bu...
Difference between natural join and inner join
...
253
One significant difference between INNER JOIN and NATURAL JOIN is the number of columns return...
What is a lambda expression in C++11?
...o write something like the following, to keep the functor local:
void func2(std::vector<int>& v) {
struct {
void operator()(int) {
// do something
}
} f;
std::for_each(v.begin(), v.end(), f);
}
however this is not allowed, f cannot be passed to a template function i...
Visual Studio debugging/loading very slow
... they load slow, they'll always load slow after that. I could be waiting 1-2 minutes or more.
52 Answers
...
How to delete items from a dictionary while iterating over it?
...ionary while iterating over it:
>>> mydict = {'one': 1, 'two': 2, 'three': 3, 'four': 4}
>>> for k, v in mydict.iteritems():
... if k == 'two':
... del mydict[k]
...
------------------------------------------------------------
Traceback (most recent call last):
File ...
Accessing bash command line args $@ vs $*
...rs are quoted. Let me illustrate the differences:
$ set -- "arg 1" "arg 2" "arg 3"
$ for word in $*; do echo "$word"; done
arg
1
arg
2
arg
3
$ for word in $@; do echo "$word"; done
arg
1
arg
2
arg
3
$ for word in "$*"; do echo "$word"; done
arg 1 arg 2 arg 3
$ for word in "$@"; do echo "$...
How to detect shake event with android?
... |
edited Jun 10 '15 at 8:27
answered Mar 11 '11 at 10:08
N...
How do I speed up the gwt compiler?
...agent" values="ie6,gecko,gecko1_8"></define-property>
or in gwt 2.x syntax, and for one browser only:
<set-property name="user.agent" value="gecko1_8"/>
This, for example, will compile your application for IE and FF only. If you know you are using only a specific browser for test...
Only read selected columns
..."NULL", 6)),
+ header = TRUE)
Year Jan Feb Mar Apr May Jun
1 2009 -41 -27 -25 -31 -31 -39
2 2010 -41 -27 -25 -31 -31 -39
3 2011 -21 -27 -2 -6 -10 -32
Change "integer" to one of the accepted types as detailed in ?read.table depending on the real type of data.
data.txt looks like th...