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Set value to NULL in MySQL
... can be inserted/updated without quotes:
INSERT INTO user (name, something_optional) VALUES ("Joe", NULL);
UPDATE user SET something_optional = NULL;
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How to close tag properly?
...es the tag properly. Best to add the alt attribute for people that are visually impaired.
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dplyr: “Error in n(): function should not be called directly”
...ction" specification, like example below:
delay <- dplyr::summarise(by_tailnum,
count = n(),
dist = mean(distance, na.rm = TRUE),
delay = mean(arr_delay, na.rm = TRUE))
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Tomcat: How to find out running tomcat version
....in/blog/check-jsp-tomcat-version
Save this code into a file called tomcat_version.jsp:
Tomcat Version : <%= application.getServerInfo() %><br>
Servlet Specification Version :
<%= application.getMajorVersion() %>.<%= application.getMinorVersion() %> <br> ...
Why is Java Vector (and Stack) class considered obsolete or deprecated?
... each individual operation. That's almost never what you want to do.
Generally you want to synchronize a whole sequence of operations. Synchronizing individual operations is both less safe (if you iterate over a Vector, for instance, you still need to take out a lock to avoid anyone else changing t...
delegate keyword vs. lambda notation
... If you specify an anonymous method without specifying a parameter list at all it is compatible with any delegate type returning void and without any out parameters. Armed with this knowledge, we should be able to construct two overloads to make the expressions completely unambiguous but very differ...
linq where list contains any in list
...
Sounds like you want:
var movies = _db.Movies.Where(p => p.Genres.Intersect(listOfGenres).Any());
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C# code to validate email address
...e-mail addresses are more forgiving than you might first assume. These are all perfectly valid forms:
cog@wheel
"cogwheel the orange"@example.com
123@$.xyz
For most use cases, a false "invalid" is much worse for your users and future proofing than a false "valid". Here's an article that used to ...
Manipulate a url string by adding GET parameters
...category'] = 2; // Overwrite if exists
$params['tags'][] = 'cool'; // Allows multiple values
// Note that this will url_encode all values
$url_parts['query'] = http_build_query($params);
// If you have pecl_http
echo http_build_url($url_parts);
// If not
echo $url_parts['scheme'] . '://' . $...
C++ templates that accept only certain types
...ply forward-declare a global template, but only define (explicitly or partially specialise) it for the valid types:
template<typename T> class my_template; // Declare, but don't define
// int is a valid type
template<> class my_template<int> {
...
};
// All pointer types...