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How to change a nullable column to not nullable in a Rails migration?
I created a date column in a previous migration and set it to be nullable. Now I want to change it to be not nullable. How do I go about doing this assuming there are null rows in that database? I'm ok with setting those columns to Time.now if they're currently null.
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Calculate difference between two datetimes in MySQL
...rence between the last login time and the current time (which I get using NOW() ).
3 Answers
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What does the exclamation mark do before the function?
...ation. You would need an invocation, foo(), to actually run the function.
Now, when we add the seemingly innocuous exclamation mark: !function foo() {} it turns it into an expression. It is now a function expression.
The ! alone doesn't invoke the function, of course, but we can now put () at the ...
Adding elements to object
I need to populate a json file, now I have something like this:
17 Answers
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Why won't my PHP app send a 404 error?
...along whatever PHP gave me
In addition to providing a 404 header, PHP is now responsible for outputting the actual 404 page.
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How do you trigger a block after a delay, like -performSelector:withObject:afterDelay:?
...ion of my block for 10 seconds.
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 10 * NSEC_PER_SEC), dispatch_get_main_queue(), ^{
NSLog(@"parameter1: %d parameter2: %f", parameter1, parameter2);
});
More: https://developer.apple.com/documentation/dispatch/1452876-dispatch_after
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How do I get current date/time on the Windows command line in a suitable format for usage in a file/
Update: Now that it's 2016 I'd use PowerShell for this unless there's a really compelling backwards-compatible reason for it, particularly because of the regional settings issue with using date . See @npocmaka's https://stackoverflow.com/a/19799236/8479
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How do I connect to this localhost from another computer on the same network?
...re the loopback interface
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127.0.0.1 symfony.local
From now on, everytime you type symfony.local on this computer, your computer will use the loopback interface to connect to symfony.local. It will understand that you want to work on localhost (127.0.0.1).
3 Access symfony.local...
Force CloudFront distribution/file update
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As of March 19, Amazon now allows Cloudfront's cache TTL to be 0 seconds, thus you (theoretically) should never see stale objects. So if you have your assets in S3, you could simply go to AWS Web Panel => S3 => Edit Properties => Metadata,...
How to store date/time and timestamps in UTC time zone with JPA and Hibernate
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With Hibernate 5.2, you can now force the UTC time zone using the following configuration property:
<property name="hibernate.jdbc.time_zone" value="UTC"/>
For more details, check out this article.
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