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count(*) vs count(column-name) - which is more correct? [duplicate]
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COUNT(*) counts all rows
COUNT(column) counts non-NULLs only
COUNT(1) is the same as COUNT(*) because 1 is a non-null expressions
Your use of COUNT(*) or COUNT(column) should be based on the desired output only.
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What is the use of having destructor as private?
...e connection being open or a file being written. You could have a "request_delete" method in the class or the manager that will check that condition and it will either delete or decline, and return a status telling you what it did. That's far more flexible that just calling "delete".
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How to initialize std::vector from C-style array?
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Don't forget that you can treat pointers as iterators:
w_.assign(w, w + len);
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How efficient can Meteor be while sharing a huge collection among many clients?
... which watches the
database for changes; and the merge box, which combines all of a
client's active subscriptions and sends them out over the network to the
client.
Publish functions
Each time a Meteor client subscribes to a collection, the server runs a
publish function. The publish function's j...
SVN command to delete all locally missing files
In SVN is there a command I can use to delete all locally missing files in a directory?
12 Answers
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What's onCreate(Bundle savedInstanceState)
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If you save the state of the application in a bundle (typically non-persistent, dynamic data in onSaveInstanceState), it can be passed back to onCreate if the activity needs to be recreated (e.g., orientation change) so that you don't lose this prior information. If no data was suppl...
How to read multiple text files into a single RDD?
... RDD. The API here is just an exposure of Hadoop's FileInputFormat API, so all the same Path options apply.
– Nick Chammas
Jun 4 '14 at 15:04
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How to detect if URL has changed after hash in JavaScript
...hange event on window.
In some old browsers, you need a timer that continually checks location.hash. If you're using jQuery, there is a plugin that does exactly that.
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Sending a message to nil in Objective-C
...I wonder what " sending a message to nil " means - let alone how it is actually useful. Taking an excerpt from the documentation:
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Regular expression to search for Gadaffi
... Libyan leader’s name spelled so many different ways?.
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To match all the names in the article you've mentioned later, this should match them all. Let's just hope it won't match a lot of other stuff :D
\b(Kh?|Gh?|Qu?)[aeu](d['dt]?|t|zz|dhd)h?aff?[iy]\b
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