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Can a foreign key be NULL and/or duplicate?
...inition. Null by definition is not a value. Null means that we do not yet know what the value is.
Let me give you a real life example. Suppose you have a database that stores sales proposals. Suppose further that each proposal only has one sales person assigned and one client. So your proposal tab...
Is it possible to set UIView border properties from interface builder?
...ou can set some properties of a view's layer through interface builder. I know that I can set a layer's borderWidth and cornerRadius through xcode. borderColor doesn't work, probably because the layer wants a CGColor instead of a UIColor.
You might have to use Strings instead of numbers, but it wor...
Cannot download Docker images behind a proxy
...tory for the Docker service:
mkdir /etc/systemd/system/docker.service.d
Now create a file called /etc/systemd/system/docker.service.d/http-proxy.conf that adds the HTTP_PROXY environment variable:
[Service]
Environment="HTTP_PROXY=http://proxy.example.com:80/"
If you have internal Docker regis...
android View not attached to window manager
... thread which survives the activity restart and may hold references to the now dead Activity and its Views (this is a effectively a memory leak, albeit probably a short term one - depends how long the task takes to complete). The solution above works fine, if you're happy to accept a short term mem...
How to implement Enums in Ruby?
...s and the first letter of the module name must be capitalized for ruby to know that the module is a module of constants.
– Rokujolady
Apr 8 '13 at 18:41
3
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Specify width in *characters*
...22 px, where 20px is the height of the font, and 2px are for line height.
Now since em and ex are of no use here, a possible strategy for a CSS-only solution would be to
Create an element containing just a  
Let it autosize itself
Place your div within and
Make it 10 times as large as t...
Modify UIImage renderingMode from a storyboard/xib file
... answered May 12 '14 at 17:31
SnowmanSnowman
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Error: Cannot pull with rebase: You have unstaged changes
...
This seemed to have work but now I am facing another error(started a new questions to not confuse future vistors): stackoverflow.com/questions/23518247/…
– user3597950
May 7 '14 at 12:47
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UIImagePickerController error: Snapshotting a view that has not been rendered results in an empty sn
...s deprecated in iOS 6. It is suggested that presentViewController be used now.
– Gallymon
Jan 23 '14 at 18:50
5
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What is the exact problem with multiple inheritance?
...s say have two classes A and B, both of which define a method doSomething. Now you define a third class C, which inherits from both A and B, but you don't override the doSomething method.
When the compiler seed this code...
C c = new C();
c.doSomething();
...which implementation of the method sh...