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Can I have multiple primary keys in a single table?
... primary key (userid, userdataid)
);
Update: Here is a link with a more detailed description of composite primary keys.
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What is the difference between HTML tags and ?
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There are already good, detailed answers here, but no visual examples, so here's a quick illustration:
<div>This is a div.</div>
<div>This is a div.</div>
<div>This is a div.</div>
<span>This is a ...
Is the pImpl idiom really used in practice?
...n keeping binary compatibility of shared libraries
hiding certain internal details
decreasing recompilation cycles
Those may or may not be real advantages to you. Like for me, I don't care about a few minutes recompilation time. End users usually also don't, as they always compile it once and from...
Difference between a Structure and a Union
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hopefully that explains in more detail what's stored in x.a when you set x.b.
– Kyle Cronin
Dec 6 '08 at 19:33
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How do you 'redo' changes after 'undo' with Emacs?
... C-/, are C-_, C-x u, and M-x undo.
See Undo in the Emacs Manual for more details on Emacs’s undo system.
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What does the “at” (@) symbol do in Python?
... do matrix multiplication, but it can be anything you want. See PEP465 for details.
This is a simple implementation of matrix multiplication.
class Mat(list):
def __matmul__(self, B):
A = self
return Mat([[sum(A[i][k]*B[k][j] for k in range(len(B)))
for j in...
best way to preserve numpy arrays on disk
...ieved fairly well using csv (which is also very portable of course).
More details and the code are available at the github repo.
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Canvas width and height in HTML5
...an answer to Stack Overflow!Please be sure to answer the question. Provide details and share your research!But avoid …Asking for help, clarification, or responding to other answers.Making statements based on opinion; back them up with references or personal experience.To learn more, see our tips o...
Does every Core Data Relationship have to have an Inverse?
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This is a great answer; thanks for spelling out in clear detail what is - from the docs, and from all I've read - the main argument in favor of having inverses for everything, even where the inverse relationship isn't humanly meaningful. This really ought to be the accepted answer....
How to determine when a Git branch was created?
... The 'git log -g <branch>' was the one that worked for me - lots of detail. Need to be on the branch to use any of these.
– Lidia
Nov 19 '15 at 1:43
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