大约有 36,010 项符合查询结果（耗时：0.0431秒） [XML]
selecting unique values from a column
...e record, the DISTINCT is worthless (unless it is an id field, and you can do a second query where id IN that list). Good news, though, if you have multiple duplicate results as a result of a JOIN you can do a GROUP BY and get the full results filtered.
– Chadwick Meyer
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SharedPreferences.onSharedPreferenceChangeListener not being called consistently
...ged(SharedPreferences prefs, String key) {
// Implementation
}
});
do this:
// Use instance field for listener
// It will not be gc'd as long as this instance is kept referenced
listener = new SharedPreferences.OnSharedPreferenceChangeListener() {
public void onSharedPreferenceChanged(Sha...
pandas dataframe columns scaling with sklearn
...ply sklearn's min_max_scaler to some of the columns. Ideally, I'd like to do these transformations in place, but haven't figured out a way to do that yet. I've written the following code that works:
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How to extract a git subdirectory and make a submodule out of it?
...veral subdirectories containing different things:
Project/paper contains a document written in LaTeX
Project/sourcecode/RailsApp contains my rails app.
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Eclipse HotKey: how to switch between tabs?
How can I switch between opened windows in Eclipse? There is Ctrl + F6 , but it's asking me which one I want, but I want switch it like tabs in browser or window in operating system ( Cmd / Win + Tab ) without file-selection from the list. How to do this easy thing in Eclipse?
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How can I present a file for download from an MVC controller?
...bForms, I would normally have code like this to let the browser present a "Download File" popup with an arbitrary file type, like a PDF, and a filename:
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Load multiple packages at once
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Several permutations of your proposed functions do work -- but only if you specify the character.only argument to be TRUE. Quick example:
lapply(x, require, character.only = TRUE)
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Confused about stdin, stdout and stderr?
... which a program writes into its requests to run a task in the process, stdout is the file into which the kernel writes its output and the process requesting it accesses the information from, and stderr is the file into which all the exceptions are entered. On opening these files to check whethe...
Laravel Eloquent: Ordering results of all()
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You can actually do this within the query.
$results = Project::orderBy('name')->get();
This will return all results with the proper order.
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log4net argument to LogManager.GetLogger
Why do most log4net examples get the logger for a class by doing this:
5 Answers
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