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event.preventDefault() vs. return false
...eturn false from within a jQuery event handler is effectively the same as calling both e.preventDefault and e.stopPropagation on the passed jQuery.Event object.
e.preventDefault() will prevent the default event from occuring, e.stopPropagation() will prevent the event from bubbling up and return f...
ORA-00979 not a group by expression
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You must put all columns of the SELECT in the GROUP BY or use functions on them which compress the results to a single value (like MIN, MAX or SUM).
A simple example to understand why this happens: Imagine you have a database like this:
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Concatenating two lists - difference between '+=' and extend()
I've seen there are actually two (maybe more) ways to concatenate lists in Python:
One way is to use the extend() method:
9...
What does 'public static void' mean in Java?
...ely different things:
public means that the method is visible and can be called from other objects of other types. Other alternatives are private, protected, package and package-private. See here for more details.
static means that the method is associated with the class, not a specific instance (...
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock'
I installed MySQL on Mac OS X Mountain Lion with homebrew install mysql , but when I tried mysql -u root I got the following error:
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How do I install ASP.NET MVC 5 in Visual Studio 2012?
Is there a way to install ASP.NET MVC 5 in Visual Studio 2012?
11 Answers
11
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How to check if an object is an array?
... {
Array.isArray = function(obj) {
return Object.prototype.toString.call(obj) === '[object Array]';
}
};
If you use jQuery you can use jQuery.isArray(obj) or $.isArray(obj). If you use underscore you can use _.isArray(obj)
If you don't need to detect arrays created in different frames you...
Is non-blocking I/O really faster than multi-threaded blocking I/O? How?
...ocking or asynchronous I/O is that your thread can continue its work in parallel. Of course you can achieve this also using an additional thread. As you stated for best overall (system) performance I guess it would be better to use asynchronous I/O and not multiple threads (so reducing thread switch...
How to install psycopg2 with “pip” on Python?
I'm using virtualenv and I need to install "psycopg2".
33 Answers
33
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Is it expensive to use try-catch blocks even if an exception is never thrown?
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try has almost no expense at all. Instead of doing the work of setting up the try at runtime, the code's metadata is structured at compile time such that when an exception is thrown, it now does a relatively expensive operation of walking up the stack an...