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Add unique constraint to combination of two columns
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Once you have removed your duplicate(s):
ALTER TABLE dbo.yourtablename
ADD CONSTRAINT uq_yourtablename UNIQUE(column1, column2);
or
CREATE UNIQUE INDEX uq_yourtablename
ON dbo.yourtablename(column1, column2);
Of course, it can often be better to c...
Does Python support multithreading? Can it speed up execution time?
...o run threads in parallel.
This only applies to Python code. C extensions can and do release the GIL to allow multiple threads of C code and one Python thread to run across multiple cores. This extends to I/O controlled by the kernel, such as select() calls for socket reads and writes, making Pytho...
nodeValue vs innerHTML and textContent. How to choose?
...nstance.
innerText didn't exist in firefox until FireFox 45 according to caniuse but is now supported in all major browsers.
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XPath to select multiple tags
...er is:
/a/b/*[self::c or self::d or self::e]
Do note that this
a/b/*[local-name()='c' or local-name()='d' or local-name()='e']
is both too-long and incorrect. This XPath expression will select nodes like:
OhMy:c
NotWanted:d
QuiteDifferent:e
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When serving JavaScript files, is it better to use the application/javascript or application/x-javas
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text/javascript is obsolete
application/x-javascript was experimental while deciding to move to…
application/javascript is the current official MIME type for JS
That said, browsers often ignore the content-type sent by the server and pay a lot of attenti...
How do I write good/correct package __init__.py files
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__all__ is very good - it helps guide import statements without automatically importing modules
http://docs.python.org/tutorial/modules.html#importing-from-a-package
using __all__ and import * is redundant, only __all__ is needed
I think one of the most powerful reasons to use import * in an __...
Why is arr = [] faster than arr = new Array?
... and disregarding VM-specific optimizations:
First, we go through the lexical analysis phase where we tokenize the code.
By way of example, the following tokens may be produced:
[]: ARRAY_INIT
[1]: ARRAY_INIT (NUMBER)
[1, foo]: ARRAY_INIT (NUMBER, IDENTIFIER)
new Array: NEW, IDENTIFIER
new Array(...
Backbone.View “el” confusion
...ds its events to the model data inside of it.
When you create a view you can manipulate the el in four ways using el:, tagName:, className:, and id:. If none of these are declared el defaults to a div without id or class. It is also not associated with the page at this point. You can change the ta...
Convert blob URL to normal URL
My page generates a URL like this: "blob:http%3A//localhost%3A8383/568233a1-8b13-48b3-84d5-cca045ae384f" How can I convert it to a normal address?
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What is the AppDelegate for and how do I know when to use it?
...he design approach implied by Andrew's use of the term "heart of your application". What I mean by this is that I think you should avoid lumping too many things in a central location -- good program design normally involves separating functionality by "area of concern".
A delegate object is an obje...