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Most efficient method to groupby on an array of objects
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answered Jan 20 '16 at 2:02
Ceasar BautistaCeasar Bautista
15.6k1111 gold badges5050 silver badges7171 bronze badges
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Why is typeof null “object”?
...s were represented as a type tag and a value. The type tag for objects was 0. null was represented as the NULL pointer (0x00 in most platforms). Consequently, null had 0 as type tag, hence the "object" typeof return value. (reference)
A fix was proposed for ECMAScript (via an opt-in), but was rejec...
Rails: select unique values from a column
...rails 5+
Model.distinct.pluck(:rating)
Update
Apparently, as of rails 5.0.0.1, it works only on "top level" queries, like above. Doesn't work on collection proxies ("has_many" relations, for example).
Address.distinct.pluck(:city) # => ['Moscow']
user.addresses.distinct.pluck(:city) # => [...
PHP操作MongoDB时的整数问题及对策 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
...;
$instance = $instance->selectCollection('test', 'test');
for ($i = 0; $i < 10; $i++) {
$instance->insert(array(
'group_id' => rand(1, 5),
'count' => rand(1, 5),
));
}
?>
下面让我们使用group操作，根据group_id分组，汇总计算count：
<?ph...
Is it possible to start a shell session in a running container (without ssh)
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schrej
42044 silver badges1010 bronze badges
answered Jul 29 '13 at 18:54
creackcreack
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How do I compile and run a program in Java on my Mac?
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190
Compiling and running a Java application on Mac OSX, or any major operating system, is very easy...
How to get a value of an element by name instead of ID
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answered Jan 21 '10 at 13:27
Nick Craver♦Nick Craver
580k125125 gold badges12551255 silver badges11351135 bronze badges
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REST URI convention - Singular or plural name of resource while creating it
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edited Jun 15 '16 at 16:10
Mathieu IKO
3544 bronze badges
answered Jul 27 '11 at 14:26
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App Inventor 2 SQLite 拓展：超流行兼容主流SQL语法的迷你本地数据库引擎 ...
...工作，因此不会阻塞主 UI 线程。这对于在可能需要超过 100 毫秒左右的操作期间获得良好的用户体验非常重要。阻塞主 UI 线程将使您的应用程序看起来“冻结”并变得无响应，用户不喜欢这样。
当您需要执行需要一段时间的数...
Just what is an IntPtr exactly?
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160
It's a "native (platform-specific) size integer." It's internally represented as void* but expos...