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What's wrong with nullable columns in composite primary keys?
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Primary keys are for uniquely identifying rows. This is done by comparing all parts of a key to the input.
Per definition, NULL cannot be part of a successful comparison. Even a comparison to itself (NULL = NULL) will fail. This means a key containing NULL would not work.
Additonally, NULL is al...
How to use string.replace() in python 3.x
... The "re" (regular expression) module has alternatives for (some? all?) deprecated string functions. In this case, re.sub().
– ToolmakerSteve
Dec 13 '13 at 22:19
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Is it more efficient to copy a vector by reserving and copying, or by creating and swapping? [duplic
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@rlbond Accidentally downvoted the answer :(, Can you please edit the post, so that i can remove the downvote and give the upvote?
– Shubham Sharma
Jul 24 at 17:32
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Ternary Operator Similar To ?:
...or that we just defined:
object T { val condition = true
import Bool._
// yay!
val x = condition ? "yes" | "no"
}
Have fun ;)
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What is the difference between HTTP_HOST and SERVER_NAME in PHP?
...T is obtained from the HTTP request header and this is what the client actually used as "target host" of the request. The SERVER_NAME is defined in server config. Which one to use depends on what you need it for. You should now however realize that the one is a client-controlled value which may thus...
What is the correct answer for cout
...r<<(std::operator<<(std::cout, a++), a);
C++ guarantees that all side effects of previous evaluations will have been performed at sequence points. There are no sequence points in between function arguments evaluation which means that argument a can be evaluated before argument std::ope...
Ruby optional parameters
...cope ||= LDAP::LDAP_SCOPE_SUBTREE
... do something ...
end
Now if you call the method as above, the behaviour will be as you expect.
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Sorting object property by values
...ou like, thus achieving exactly what you set out to do. That would work in all the browsers I know of, but it would be dependent on an implementation quirk, and could break at any time. You should never make assumptions about the order of elements in a JavaScript object.
var objSorted = {}
sortable....
Run a string as a command within a Bash script
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eval is an evil command in all programming languages so use it with caution.
– Krishnadas PC
Jul 17 '18 at 6:50
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How to install PyQt4 on Windows using pip?
...ld than just a pure python code package, which means it can be hard to install it from source.
Make sure you grab the correct Windows wheel file (python version, 32/64 bit), and then use pip to install it - e.g:
C:\path\where\wheel\is\> pip install PyQt4-4.11.4-cp35-none-win_amd64.whl
Should ...