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Add Foreign Key to existing table
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To add a foreign key (grade_id) to an existing table (users), follow the following steps:
ALTER TABLE users ADD grade_id SMALLINT UNSIGNED NOT NULL DEFAULT 0;
ALTER TABLE users ADD CONSTRAINT fk_grade_id FOREIGN KEY (grade_id) REFERENCES grades(id);
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Undoing a 'git push'
... highly dangerous if you are working in a shared repo. As a best practice, all commits pushed to a remote repo that is shared should be considered 'immutable'. Use 'git revert' instead: kernel.org/pub/software/scm/git/docs/…
– Saboosh
Jan 13 '12 at 20:47
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Is it possible to use argsort in descending order?
... this method is that ids is a view of avgDists:
>>> ids.flags
C_CONTIGUOUS : False
F_CONTIGUOUS : False
OWNDATA : False
WRITEABLE : True
ALIGNED : True
UPDATEIFCOPY : False
(The 'OWNDATA' being False indicates this is a view, not a copy)
Another way to do this is something ...
Unsubscribe anonymous method in C#
...ered Oct 8 '08 at 15:33
Jacob KrallJacob Krall
24.8k66 gold badges5757 silver badges7373 bronze badges
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@ variables in Ruby on Rails
...cope (current block)
@title is an instance variable - and is available to all methods within the class.
You can read more here:
http://strugglingwithruby.blogspot.dk/2010/03/variables.html
In Ruby on Rails - declaring your variables in your controller as instance variables (@title) makes them ava...
How do I clone a Django model instance object and save it to the database?
...imary key of your object and run save().
obj = Foo.objects.get(pk=<some_existing_pk>)
obj.pk = None
obj.save()
If you want auto-generated key, set the new key to None.
More on UPDATE/INSERT here.
Official docs on copying model instances: https://docs.djangoproject.com/en/2.2/topics/db/que...
How do I pass a method as a parameter in Python
...thodToRun()
return result
obj.method2(obj.method1)
Note: I believe a __call__() method does exist, i.e. you could technically do methodToRun.__call__(), but you probably should never do so explicitly. __call__() is meant to be implemented, not to be invoked from your own code.
If you wanted me...
Django: “projects” vs “apps”
...views.py
and so on. Would it help if I said views.py doesn't have to be called views.py? Provided you can name, on the python path, a function (usually package.package.views.function_name) it will get handled. Simple as that. All this "project"/"app" stuff is just python packages.
Now, how are yo...
AngularJS For Loop with Numbers & Ranges
... You have to watch out for things like this. The range function will get called multiple times for each item in the list. You can get nasty memory leaks and you're generating a lot of function calls. It almost seems easier to put the collection inside the controller.
– Lucas ...
What are best practices that you use when writing Objective-C and Cocoa? [closed]
...rogramming practices do you use when writing Objective-C, and more specifically when using Cocoa (or CocoaTouch).
33 Answer...