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postgresql - sql - count of `true` values
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Yuk. That fix is really confusing. AFAICS, it will now count true or null values. I think that rephrasing it so that you always have nullif([boolean expression], false) makes it much easier to read. You can then vary the boolean expression part to be whatever you like, in th...
常用Linux命令详解（持续更新） - 更多技术 - 清泛网 - 专注C/C++及内核技术
...作，详细的命令参数请输入：shutdown -h 进行查看
shutdown now 关机命令
shutdown -r now 关机重启命令
3. 重新启动计算机的命令
reboot
用来重新启动系统，直接输入reboot即可
4. 新建用户的命令
useradd kedacom 新增一个kedacom...
Pretty-print an entire Pandas Series / DataFrame
...n printed. If the above answer did not work for previous versions, it does now.
– H Froedge
Sep 28 '18 at 7:02
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Can I have onScrollListener for a ScrollView?
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Every instance of View calls getViewTreeObserver(). Now when holding an instance of ViewTreeObserver, you can add an OnScrollChangedListener() to it using the method addOnScrollChangedListener().
You can see more information about this class here.
It lets you be aware of eve...
How do I check in JavaScript if a value exists at a certain array index?
...e
if (i >= 0 && i < array.length) {
// it is in array
}
Now, under the hood, JavaScript engines almost certainly won't allocate array space linearly and contiguously like this, as it wouldn't make much sense in a dynamic language and it would be inefficient for certain code. They...
How to center a “position: absolute” element
... element that has the attribute position set to absolute .
Does anyone know why the images are not centered?
26 Answers
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Combine two ActiveRecord::Relation objects
...ed).where(id: [6, 7])
current_user.posts.union("published_at < ?", Time.now)
user_1.posts.union(user_2.posts).union(Post.published)
user_1.posts.union_all(user_2.posts)
share
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improve this answ...
How to create a Menubar application for Mac
...swer it's popularity has exploded (52 contributors currently) and there is now even a distributable version with which you can package your own plugins.
A very simple (non-interactive) example to show live Bitcoin price:
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Display back button on action bar
...is way, you don't go back even if you start previous activity again having now one instace of it more and you go always forward and forward until stack overflow happens if you continua long enough. I think Igor's answer is correct you should stop this activity with finish() and let framework get y...
UIView Hide/Show with animation
...n your app and add #import <QuartzCore/QuartzCore.h> to your header. Now you can do one of the following:
1) set button.layer.shouldRasterize = YES; and then use the alpha animation code that Michail provided in his answer. This will prevent the layers from blending weirdly, but has a slight ...