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SQL - using alias in Group By
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SQL is implemented as if a query was executed in the following order:
FROM clause
WHERE clause
GROUP BY clause
HAVING clause
SELECT clause
ORDER BY clause
For most relational database systems, this order explains which names ...
How do I avoid capturing self in blocks when implementing an API?
...eading to a retain cycle. I've made a simple code sample to illustrate the issue. I believe I understand what this means but I'm not sure the "correct" or recommended way to implement this type of scenario.
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What is the difference between required and ng-required?
What is the difference between required and ng-required (form validation)?
3 Answers
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How do I test for an empty JavaScript object?
....length === 0 && obj.constructor === Object
Note, though, that this creates an unnecessary array (the return value of keys).
Pre-ECMA 5:
function isEmpty(obj) {
for(var prop in obj) {
if(obj.hasOwnProperty(prop)) {
return false;
}
}
return JSON.stringify(obj) === JSO...
HashMap to return default value for non-found keys?
Is it possible to have a HashMap return a default value for all keys that are not found in the set?
14 Answers
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Measure time in Linux - time vs clock vs getrusage vs clock_gettime vs gettimeofday vs timespec_get?
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The problem is that there are several different time functions available in C and C++, and some of them vary in behavior between implementations. There are also a lot of half-answers floating around. Compiling a list of clock functions...
Does Android support near real time push notification?
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Firebase Cloud Messaging FCM FAQ is the new version of GCM. It inherits GCM’s core infrastructure to deliver messages reliably on Android, iOS and Chrome. However they'll continue to support GCM because lot of developers are using GCM SDKs today to handle ...
Java Timestamp - How can I create a Timestamp with the date 23/09/2007?
...y Timestamp, I presume you mean java.sql.Timestamp. You will notice that this class has a constructor that accepts a long argument. You can parse this using the DateFormat class:
DateFormat dateFormat = new SimpleDateFormat("dd/MM/yyyy");
Date date = dateFormat.parse("23/09/2007");
long time = date...
Comparing two java.util.Dates to see if they are in the same day
...te s (e.g. date1 and date2 ) and come up with a boolean sameDay which is true of the two Date s share the same day, and false if they are not.
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Copy / Put text on the clipboard with FireFox, Safari and Chrome
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There is now a way to easily do this in most modern browsers using
document.execCommand('copy');
This will copy currently selected text. You can select a textArea or input field using
document.getElementById('myText').select(...