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conditional unique constraint
...re i need to enforce a unique constraint on a set of columns, but only for one value of a column.
6 Answers
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Most lightweight way to create a random string and a random hexadecimal number
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I got a faster one for the hex output. Using the same t1 and t2 as above:
>>> t1 = timeit.Timer("''.join(random.choice('0123456789abcdef') for n in xrange(30))", "import random")
>>> t2 = timeit.Timer("binascii.b2a_hex(o...
What's the difference between ConcurrentHashMap and Collections.synchronizedMap(Map)?
...ng at the source code, the synchronized map is only an implementation with one mutex (blocking) while the ConcurrentHashMap is more complex to deal with concurrent access
– Vinze
Feb 4 '09 at 9:36
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Placement of the asterisk in pointer declarations
...'ve recently decided that I just have to finally learn C/C++, and there is one thing I do not really understand about pointers or more precisely, their definition.
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How to use git bisect?
... was working at the revision 0. So the regression was likely introduced in one of the commits 1, 2, 3, 4, 5, current.
You could try to check out each commit, build it, check if the regression is present or not. If there is a large number of commits, this can take a long time. This is a linear searc...
vector vs. list in STL
...that I didn't want the OP to think that the interface is not there in case one wants to shoot himself in the (performance) foot.
– Manuel
Feb 5 '10 at 18:22
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“Notice: Undefined variable”, “Notice: Undefined index”, and “Notice: Undefined offset” using PHP
...value of an uninitialized variable is problematic in the case of including one file into another which uses the same variable name. It is also a major security risk with register_globals turned on. E_NOTICE level error is issued in case of working with uninitialized variables, however not in the cas...
What characters are forbidden in Windows and Linux directory names?
...r-case and lower-case characters, so you cannot create a folder named A if one named a already exists. Worse, seemingly-allowed names like PRN and CON, and many others, are reserved and not allowed. Windows also has several length restrictions; a filename valid in one folder may become invalid if mo...
In jQuery, how do I select an element by its name attribute?
...iobutton value when clicking on it using jQuery?". A small difference, but one that baffled me for a bit.
– gargantuan
Mar 2 '12 at 10:13
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How to manage client-side JavaScript dependencies? [closed]
...score: "http://underscorejs.org/underscore-min.js", // Remote
backbone: "https://github.com/documentcloud/backbone/blob/master/backbone-min.js" // Remote on github
},
shim: {
backbone: {
deps: ["underscore", "jquery"] // Backbone depends on jquery and underscore
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