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Can a foreign key be NULL and/or duplicate?
...inition. Null by definition is not a value. Null means that we do not yet know what the value is.
Let me give you a real life example. Suppose you have a database that stores sales proposals. Suppose further that each proposal only has one sales person assigned and one client. So your proposal tab...
How is Racket different from Scheme?
...This answer should be updated. Racket's feature set far outweighs Scheme's now, with modules and language definitions, etc.
– CinchBlue
Dec 11 '17 at 2:57
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How to create abstract properties in python abstract classes
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Since Python 3.3 a bug was fixed meaning the property() decorator is now correctly identified as abstract when applied to an abstract method.
Note: Order matters, you have to use @property before @abstractmethod
Python 3.3+: (python docs):
class C(ABC):
@property
@abstractmethod
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How to change the order of DataFrame columns?
... with a list of the columns, rearranged as needed.
This is what you have now:
In [6]: df
Out[6]:
0 1 2 3 4 mean
0 0.445598 0.173835 0.343415 0.682252 0.582616 0.445543
1 0.881592 0.696942 0.702232 0.696724 0.373551 0.670208
2 0.662527 ...
What's a correct and good way to implement __hash__()?
...on, this is about as fast as any hash can be. Sure, if the attributes are known to be integers, and there aren't too many of them, I suppose you could potentially run slightly faster with some home-rolled hash, but it likely wouldn't be as well distributed. hash((self.attr_a, self.attr_b, self.attr_...
Importing a Maven project into Eclipse from Git
..., so you end up with dozens of copies of the almost-identical package, and now adding an "m2e marketplace" doesn't make things better.
– Has QUIT--Anony-Mousse
Mar 30 '13 at 12:12
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Prevent RequireJS from Caching Required Scripts
...se the URL has changed and Chrome has dropped the breakpoint. I'd love to know a client-only workaround to this.
– Drew Noakes
Mar 13 '13 at 19:12
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Everyauth vs Passport.js?
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Ironically, but passport has much more issues now: github.com/jaredhanson/passport/issues (273 vs. 148 for everyauth).
– Anton Bessonov
Jul 29 '18 at 19:43
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Unsupported major.minor version 52.0 [duplicate]
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"J2SE" was only used till Java 1.5 and is nowadays called "Java SE", see en.wikipedia.org/wiki/Java_Platform,_Standard_Edition
– Tim Büthe
Sep 6 '16 at 14:38
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Pass Method as Parameter using C#
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@unknown: In that case it would be Action instead of Func<string, int>.
– Jon Skeet
Jan 17 '10 at 21:45
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