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Can a foreign key be NULL and/or duplicate?
...at field must exist first in a different table (the parent table). That is all an FK is by definition. 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 furth...
Object.getOwnPropertyNames vs Object.keys
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There is a little difference. Object.getOwnPropertyNames(a) returns all own properties of the object a. Object.keys(a) returns all enumerable own properties. It means that if you define your object properties without making some of them enumerable: false these two methods will give you the sa...
Replace whitespaces with tabs in linux
...long options are mandatory for short options
too.
-a, --all
convert all blanks, instead of just initial blanks
--first-only
convert only leading sequences of blanks (overrides -a)
-t, --tabs=N
have tabs N characters apart i...
How do you do block comments in YAML?
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The syntax differences are subtle and seldom arise in practice: JSON allows extended charactersets like UTF-32, YAML requires a space after separators like comma, equals, and colon while JSON does not, and some non-standard implementations of JSON extend the grammar to include Javascript's /* ...
Resuming git-svn clone
...t and slept on me. Is there a way to resume the operation without redoing all of the initial work?
4 Answers
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How to remove a file from version control without deleting it?
...ory. In the event you wish to remove files from the repo, BUT keep them locally on your machine then you'd use the flag above.
– Greg Hilston
Feb 22 '16 at 13:31
6
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Get Specific Columns Using “With()” Function in Laravel Eloquent
...n this case) needs to be the first param in the
$query->select() to actually retrieve the necessary results.*
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Why are Where and Select outperforming just Select?
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+1 for being the only answer (so far) that actually addresses the question, doesn't guess the answer and doesn't just generate "me too!" statistics.
– Binary Worrier
Aug 20 '13 at 13:21
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How to build a Debian/Ubuntu package from source?
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you can use the special package "checkinstall" for all packages which are not even in debian/ubuntu yet.
You can use "uupdate" (apt-get install devscripts) to build a package from source with existing debian sources:
Example for libdrm2:
apt-get build-dep libdrm2
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How to set iPhone UIView z index?
...will bring the view to the top, but this is only the case if the views are all siblings in the hierarchy.
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