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What's wrong with nullable columns in composite primary keys?
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In order for a foreign key to work the refered must be unique (ie. all values must be distinct). Which means that it could have a single null value. All the null values could then refer to that single null if the REFERENCES woul...
In pure functional languages, is there an algorithm to get the inverse function?
...x,-x]) [1..] will work, as this runs through the integers in the following order [0,1,-1,2,-2,3,-3, and so on]. Indeed inv (0 : concatMap (\x -> [x,-x]) [1..]) (+1) (-3) promptly returns -4!
The Control.Monad.Omega package can help you run through lists of tuples etcetera in a good way; I'm sure...
程序员才能听得懂的笑话 - 轻松一刻 - 清泛网 - 专注C/C++及内核技术
...这个论坛的人都吵起来,我今晚就跟你走. 某软件工程师:PHP是最好的语言! 某论坛炸锅了,各种吵架... 某女:服了你了,我们走吧 你想干啥都行. 某软件工程师:今天不行,我一定要说服他们,PHP必须是最好的语言 某女：....
50、《c++程...
jQuery - Detect value change on hidden input field
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It is possible to use Object.defineProperty() in order to redefine the 'value' property of the input element and do anything during its changing.
Object.defineProperty() allows us to define a getter and setter for a property, thus controlling it.
replaceWithWrapper($("#hi...
How to update column with null value
...ed Oct 6 '10 at 8:11
Daniel VassalloDaniel Vassallo
301k6666 gold badges475475 silver badges424424 bronze badges
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Stack, Static, and Heap in C++
...not concern about that now. That's meant by the term static initialization order fiasco.
Dynamic storage duration
The last storage duration is dynamic. You use it if you want to have objects live on another isle, and you want to put pointers around that reference them. You also use them if your...
HTML if image is not found
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Seems works in all major browsers. Just swap default and original. So that object renders original image and img default one
– Evgeny
Dec 16 '14 at 10:28
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Reload .profile in bash shell script (in unix)?
...A COMMON MISTAKE AND CAUSES A LOT OF DEVELOPERS TO LOSE A LOT OF TIME.
In order for your changes applied in your script to have effect for the global environment the script has to be run with
.myscript.sh
command.
In order to make sure that you script is not runned in a subshel you can use thi...
setuptools: package data folder location
...package_data, to avoid the problems described in samplebias answer, but in order to mantain the file structure you should add to your setup.py:
try:
os.symlink('../../data', 'src/mypackage/data')
setup(
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package_data = {'mypackage': ['data/*']}
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)
finally:
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How do I replace text inside a div element?
I need to set the text within a DIV element dynamically. What is the best, browser safe approach? I have prototypejs and scriptaculous available.
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