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MySQL Error 1215: Cannot add foreign key constraint
... Explosion Pill's answer covers the basics. You want to make sure to start from there. However, there are more, much more subtle cases to look out for:
For example, when you try to link up PRIMARY KEYs of different tables, make sure to provide proper ON UPDATE and ON DELETE options. E.g.:
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PRIM...
Efficient list of unique strings C#
...)
orderList.Add(item);
When removing items, make sure to remove them from both. Thus, as long as you can be sure that nothing else added items to the list, you'll have an insertion-ordered unique set!
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No Multiline Lambda in Python: Why not?
... they could force the use of parentheses if you want to return a tuple from a lambda. IMO, this should have always been enforced to prevent such ambiguities, but oh well.
– mpen
Jul 28 '12 at 23:28
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redis-py : What's the difference between StrictRedis() and Redis()?
...tRedis.
2017-03-31
Here are the specifics of the backwards compatibility, from the github.com link cited:
In addition to the changes above, the Redis class, a subclass of StrictRedis, overrides several other commands to provide backwards compatibility with older versions of redis-py:
LREM: Order o...
Bootstrap 3 Flush footer to bottom. not fixed
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There is a simplified solution from bootstrap here (where you don't need to create a new class): http://getbootstrap.com/examples/sticky-footer-navbar/
When you open that page, right click on a browser and "View Source" and open the sticky-footer-navbar.c...
Android LocationClient class is deprecated but used in documentation
...an use LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient) from OnConnected
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Java Timestamp - How can I create a Timestamp with the date 23/09/2007?
...milliseconds. Use the static method valueOf if you want to get a timestamp from a string.
– Hazok
Dec 16 '14 at 1:59
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NameError: name 'reduce' is not defined in Python
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You can add
from functools import reduce
before you use the reduce.
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Objective-C declared @property attributes (nonatomic, copy, strong, weak)
...e threadsafe accessors so atomic variables are threadsafe (can be accessed from multiple threads without botching of data)
Copy
copy is required when the object is mutable. Use this if you need the value of the object as it is at this moment, and you don't want that value to reflect any changes made...
How to get the home directory in Python?
...nt to use os.path.expanduser.
This will ensure it works on all platforms:
from os.path import expanduser
home = expanduser("~")
If you're on Python 3.5+ you can use pathlib.Path.home():
from pathlib import Path
home = str(Path.home())
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