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@UniqueConstraint annotation in Java
...
To ensure a field value is unique you can write
@Column(unique=true)
String username;
The @UniqueConstraint annotation is for annotating multiple unique keys at the table level, which is why you get an error when applying it to a field.
References (JPA TopLink):
@UniqueConstraint
@Column
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How can I implement a tree in Python?
...ibility with Py3. Here we're talking about Py3 code. There's no need to do extra, legacy typing.
– cfi
Sep 27 '12 at 10:45
13
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Why can Java Collections not directly store Primitives types?
...tion of primitives. Even in the few cases where I might have wanted to the extra time and space costs of using the reference objects has been negligible. In particular I find that many people think they want Map<int,T>, forgetting that an array will do that trick very nicely.
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How to add test coverage to a private constructor?
...of coverage is to give you a level of confidence, and to suggest areas for extra testing. Artificially calling an otherwise unused constructor doesn't help with either of those points.
– Jon Skeet
Dec 23 '10 at 20:54
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Compare two files in Visual Studio
...ven combine it with the script to gain elevated rights, with only a little extra effort.
MSDN References:
Usage of diff window
Visual Studio's Diff parameter
*) Footnote: Because vsPath (the path to DEVENV.exe) differs depending on your version of Visual Studio, I am describing how you can fi...
完美解决phpcms批量移动内容后，新闻心情、评论排行等不更新的问题 - 更多...
... $tree->init($categorys);
$string .= $tree->get_tree(0, $str);
$str = "<option value='\$catid'>\$spacer \$catname</option>";
$source_string = '';
$tree->init($categorys);
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Select which href ends with some string
... can use the built-in method querySelectorAll instead. Almost all selector strings used for jQuery work with DOM methods as well:
const anchors = document.querySelectorAll('a[href$="ABC"]');
Or, if you know that there's only one matching element:
const anchor = document.querySelector('a[href$="A...
Selecting data frame rows based on partial string match in a column
I want to select rows from a data frame based on partial match of a string in a column, e.g. column 'x' contains the string "hsa". Using sqldf - if it had a like syntax - I would do something like:
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What's the difference between Ruby's dup and clone methods?
...e object, but where the apple object references other objects (such as the String object color), those references are not copied. Instead, apple and orange both reference the same object! In our example, the reference is the string object 'red'. When orange uses the append method, <<, to modif...
How to hide action bar before activity is created, and then show it again?
... super.onPostResume();
getActionBar().hide();
but it may need some extra logic to check if this is the first showing of the Activity.
The idea is to delay a little the hiding of the ActionBar. In a way we let the ActionBar be shown, but then hide it immediately. Thus we go beyond the first ...