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INNER JOIN vs LEFT JOIN performance in SQL Server
... that uses INNER JOIN on 9 tables, anyway this command takes a very long time (more than five minutes). So my folk suggested me to change INNER JOIN to LEFT JOIN because the performance of LEFT JOIN is better, despite what I know. After I changed it, the speed of query got significantly improved.
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What is the correct answer for cout
...rantees that all side effects of previous evaluations will have been performed at sequence points. There are no sequence points in between function arguments evaluation which means that argument a can be evaluated before argument std::operator<<(std::cout, a++) or after. So the result of the a...
How do I find the duplicates in a list and create another list with them?
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To remove duplicates use set(a). To print duplicates, something like:
a = [1,2,3,2,1,5,6,5,5,5]
import collections
print([item for item, count in collections.Counter(a).items() if count > 1])
## [1, 2, 5]
Note that Counter is not particularly efficient (timings) and probab...
What’s the difference between ScalaTest and Scala Specs unit test frameworks?
Both are BDD (Behavior Driven Development) capable unit test frameworks for Scala written in Scala. And Specs is built upon may also involve the ScalaTest framework. But what does Specs offer ScalaTest doesn't? What are the differences?
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Is multiplication and division using shift operators in C actually faster?
...e code sequence is. It's even possible that the processor itself has implemented the multiply instruction as a sequence of shifts & adds in microcode.
Bottom line--don't spend a lot of time worrying about this. If you mean to shift, shift. If you mean to multiply, multiply. Do what is seman...
How can I add reflection to a C++ application?
I'd like to be able to introspect a C++ class for its name, contents (i.e. members and their types) etc. I'm talking native C++ here, not managed C++, which has reflection. I realise C++ supplies some limited information using RTTI. Which additional libraries (or other techniques) could supply this ...
What is the purpose of wrapping whole Javascript files in anonymous functions like “(function(){ … }
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It's usually to namespace (see later) and control the visibility of member functions and/or variables. Think of it like an object definition. The technical name for it is an Immediately Invoked Function Expression (IIFE). jQuery plugins are us...
How does the compilation/linking process work?
... is why it must be used with care.
It works on one C++ source file at a time by replacing #include directives with the content of the respective files (which is usually just declarations), doing replacement of macros (#define), and selecting different portions of text depending of #if, #ifdef and #...
C++ - passing references to std::shared_ptr or boost::shared_ptr
...t;foo> &sp) //Again, no copy here
{
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sp->do_something();
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}
How do you know that sp->do_something() will not blow up due to a null pointer?
It all depends what is in those '...' sections of the code. What if you call something during the first '...' that...
What is the real overhead of try/catch in C#?
So, I know that try/catch does add some overhead and therefore isn't a good way of controlling process flow, but where does this overhead come from and what is it's actual impact?
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