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Retrieving the last record in each group - MySQL
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MySQL 8.0 now supports windowing functions, like almost all popular SQL implementations. With this standard syntax, we can write greatest-n-per-group queries:
WITH ranked_messages AS (
SELECT m.*, ROW_NUMBER() OVER (PARTITION BY name ORDER BY id DESC) AS rn
FROM messages AS m...
What is attr_accessor in Ruby?
I am having a hard time understanding attr_accessor in Ruby .
Can someone explain this to me?
19 Answers
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Easiest way to check for an index or a key in an array?
... associative array)
[ ${array[key]+abc} ] && echo "exists"
Basically what ${array[key]+abc} does is
if array[key] is set, return abc
if array[key] is not set, return nothing
References:
See Parameter Expansion in Bash manual and the little note
if the colon is omitted, the ope...
How do I mock the HttpContext in ASP.NET MVC using Moq?
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HttpContext is read-only, but it is actually derived from the ControllerContext, which you can set.
controller.ControllerContext = new ControllerContext( context.Object, new RouteData(), controller );
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How to compare if two structs, slices or maps are equal?
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@GeneralLeeSpeaking that's not true. From the cmp documentation: "Pointers are equal if the underlying values they point to are also equal"
– Ilia Choly
Dec 29 '18 at 18:11
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Could not load file or assembly or one of its dependencies
...ncing an old version of unity. For example let's say you have an assembly called ServiceLocator.dll which needs an old version of Unity assembly, now when you reference the ServiceLocator you should provide it with the old version of Unity, and that makes the problem.
May be the output folder where ...
Sorting a set of values [closed]
... not surprising that set means "sorted list", and you have to say unordered_set to mean "set"…
– abarnert
Jul 3 '13 at 21:33
2
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ctypes - Beginner
...o testlib.so -fPIC testlib.c
# or... for Mac OS X
$ gcc -shared -Wl,-install_name,testlib.so -o testlib.so -fPIC testlib.c
Then, write a wrapper using ctypes:
testlibwrapper.py
import ctypes
testlib = ctypes.CDLL('/full/path/to/testlib.so')
testlib.myprint()
Now execute it:
$ python testlibwrap...
What does Provider in JAX-RS mean?
...tomizing the JAX-RS runtime. You can think of them as plugins that (potentially) alter the behavior of the runtime, in order to accomplish a set of (program defined) goals.
Providers are not the same as resources classes, they exist, conceptually, at a level in-between resources classes and the JAX...
How do you clear a stringstream variable?
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For all the standard library types the member function empty() is a query, not a command, i.e. it means "are you empty?" not "please throw away your contents".
The clear() member function is inherited from ios and is used to cle...