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How does MySQL process ORDER BY and LIMIT in a query?
...t used it in a production environment, but now when I bench marked it, the extra sorting does not impact the performance.
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Declaration/definition of variables locations in ObjectiveC?
...In ObjC, they should only be used to declare constants, and generally only string constants. For instance:
extern NSString * const MYSomethingHappenedNotification;
You would then in your .m file declare the actual constant:
NSString * const MYSomethingHappenedNotification = @"MYSomethingHappened...
scheduleAtFixedRate vs scheduleWithFixedDelay
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I could not understand the "extra" word mentioned in scheduleAtFixedRate time series diagram.
– MuneshSingh
Mar 25 '18 at 6:39
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Counting DISTINCT over multiple columns
... the columns, then get the distinct count of instances of the concatenated string.
SELECT count(DISTINCT concat(DocumentId, DocumentSessionId)) FROM DocumentOutputItems;
In MySQL you can do the same thing without the concatenation step as follows:
SELECT count(DISTINCT DocumentId, DocumentSessio...
How to vertically center divs? [duplicate]
...ng with a 'display: inline-box'. The line-height of the contents can cause extra space below the inline-box, and the result is that the child is aligned slightly above centre. I am not sure what part of the html spec causes this, but I found it to be unobvious and it took a while to work out the rea...
Django class-based view: How do I pass additional parameters to the as_view method?
...m urls.py
https://docs.djangoproject.com/en/1.7/topics/http/urls/#passing-extra-options-to-view-functions
This also works for generic views. Example:
url(r'^$', views.SectionView.as_view(), { 'pk': 'homepage', 'another_param':'?'}, name='main_page'),
In this case the parameters passed to the vi...
SQL query to select dates between two dates
...etween '2011/02/25' and '2011/02/27'
The date values need to be typed as strings.
To ensure future-proofing your query for SQL Server 2008 and higher, Date should be escaped because it's a reserved word in later versions.
Bear in mind that the dates without times take midnight as their defaults,...
What size do you use for varchar(MAX) in your parameter declaration?
...
cmd.Parameters.Add("@blah", OleDbType.LongVarChar, -1).Value = "very big string";
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javascript set a variable if undefined
...number') ? getVariable : 0;
In this case if getVariable is not a number (string, object, whatever), setVariable is set to 0
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How to avoid installing “Unlimited Strength” JCE policy files when deploying an application?
... // This matches Oracle Java 7 and 8, but not Java 9 or OpenJDK.
final String name = System.getProperty("java.runtime.name");
final String ver = System.getProperty("java.version");
return name != null && name.equals("Java(TM) SE Runtime Environment")
&& ver !=...