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Difference between EXISTS and IN in SQL?
...turns purely Boolean values, which is always faster than having to compare strings or values larger than a BIT/Boolean type. IN may or may not be a Boolean comparison. Since programming prefers EXPLICIT usage for stability (part of ACID), EXISTS is preferred generally.
– clift...
Get JSF managed bean by name in any Servlet related class
...follows:
@SuppressWarnings("unchecked")
public static <T> T findBean(String beanName) {
FacesContext context = FacesContext.getCurrentInstance();
return (T) context.getApplication().evaluateExpressionGet(context, "#{" + beanName + "}", Object.class);
}
and can be used as follows:
Bean...
How to get active user's UserDetails
...Authentication doesn't strictly have to contain a UserDetails. It can be a string or any other type.
If you don't want to call SecurityContextHolder directly, the most elegant approach (which I would follow) is to inject your own custom security context accessor interface which is customized to mat...
Best way to add comments in erb
..."www.some-url.com"> <input id="data" name="data" value="<%=# "String" %>"> <input type="submit" value="Send"> </form> </body> </html> throws an error
– Epigene
Feb 26 '15 at 11:14
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Using querySelectorAll to retrieve direct children
...support one code path that really just wants to take an arbitrary selector string as input and a list of matches as output! But if like me you ended up asking this question simply because you got stuck thinking "all you had was a hammer" don't forget there are a variety of other tools the DOM offers...
Linux find file names with given string
... files in the current directory and subdirectories whose name contains the string "John". I know that grep can match the content in the files, but I have no idea how to use it with file names. Any help would be appreciated.
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How to use multiple @RequestMapping annotations in spring?
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@RequestMapping has a String[] value parameter, so you should be able to specify multiple values like this:
@RequestMapping(value={"", "/", "welcome"})
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String concatenation in MySQL
...ame FROM test.student
As @eggyal pointed out in comments, you can enable string concatenation with the || operator in MySQL by setting the PIPES_AS_CONCAT SQL mode.
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Changing names of parameterized tests
...se change the name of parameterized tests, you say:
@Parameters(name="namestring")
namestring is a string, which can have the following special placeholders:
{index} - the index of this set of arguments. The default namestring is {index}.
{0} - the first parameter value from this invocation of...
How do malloc() and free() work?
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@Juergen But when free() read extra byte which contain information how much memory allocated from malloc, it get 4. Then how crash happened or how free() touch administrative data ?
– Undefined Behaviour
Aug 5 '16 at...