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What is the difference between HAVING and WHERE in SQL?
What is the difference between HAVING and WHERE in an SQL SELECT statement?
20 Answers
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Factors in R: more than an annoyance?
... data types in R is factors. In my experience factors are basically a pain and I never use them. I always convert to characters. I feel oddly like I'm missing something.
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RegEx for matching UK Postcodes
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I'd recommend taking a look at the UK Government Data Standard for postcodes [link now dead; archive of XML, see Wikipedia for discussion]. There is a brief description about the data and the attached xml schema provides a regular expression. It may not be exactly what you want bu...
What is the significance of load factor in HashMap?
HashMap has two important properties: size and load factor . I went through the Java documentation and it says 0.75f is the initial load factor. But I can't find the actual use of it.
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C# Set collection?
...set operations. A set is a collection that contains no duplicate elements, and whose elements are in no particular order...
The capacity of a HashSet(Of T) object is the number of elements that the object can hold. A HashSet(Of T) object's capacity automatically increases as elements are ad...
Java exception not caught?
...ptly for reason S, then the try statement completes abruptly for reason S (and reason R is discarded).
So, when there is a catch block that throws an exception:
try {
// ...
} catch (Exception e) {
throw new Exception("2");
}
but there is also a finally block that also throws an exceptio...
How to test that no exception is thrown?
...I have noticed this question garners interest from time to time so I'll expand a little.
Background to unit testing
When you're unit testing it's important to define to yourself what you consider a unit of work. Basically: an extraction of your codebase that may or may not include multiple methods...
How do I pass a variable by reference?
...n seems unclear about whether parameters are passed by reference or value, and the following code produces the unchanged value 'Original'
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How can I exclude directories from grep -R?
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SOLUTION 1 (combine find and grep)
The purpose of this solution is not to deal with grep performance but to show a portable solution : should also work with busybox or GNU version older than 2.5.
Use find, for excluding directories foo and bar :
find...
How to handle screen orientation change when progress dialog and background thread active?
...re starting, it pops up a progress dialog. The dialog is dismissed on the handler. This all works fine, except when screen orientation changes while the dialog is up (and the background thread is going). At this point the app either crashes, or deadlocks, or gets into a weird stage where the app doe...