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Swapping column values in MySQL
...t. This method doesn't swap the values if one of them is NULL. Use method #3 that doesn't have this limitation.
UPDATE swap_test SET x=y, y=@temp WHERE (@temp:=x) IS NOT NULL;
This method was offered by Dipin in, yet again, the comments of http://beerpla.net/2009/02/17/swapping-column-values-in-mys...
Move the most recent commit(s) to a new branch with Git
... existingbranch
git merge master
git checkout master
git reset --hard HEAD~3 # Go back 3 commits. You *will* lose uncommitted work.
git checkout existingbranch
Moving to a new branch
WARNING: This method works because you are creating a new branch with the first command: git branch newbranch. If yo...
how to concatenate two dictionaries to create a new one in Python? [duplicate]
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Slowest and doesn't work in Python3: concatenate the items and call dict on the resulting list:
$ python -mtimeit -s'd1={1:2,3:4}; d2={5:6,7:9}; d3={10:8,13:22}' \
'd4 = dict(d1.items() + d2.items() + d3.items())'
100000 loops, best of 3: 4.93 usec per loop...
Is passing 'this' in a method call accepted practice in java
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answered Jul 3 '13 at 7:16
Denys SéguretDenys Séguret
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What is the reason for having '//' in Python? [duplicate]
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In Python 3, they made the / operator do a floating-point division, and added the // operator to do integer division (i.e. quotient without remainder); whereas in Python 2, the / operator was simply integer division, unless one of the ...
Get difference between two lists
...))
Out[5]: ['Four', 'Three']
Beware that
In [5]: set([1, 2]) - set([2, 3])
Out[5]: set([1])
where you might expect/want it to equal set([1, 3]). If you do want set([1, 3]) as your answer, you'll need to use set([1, 2]).symmetric_difference(set([2, 3])).
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How to print a number with commas as thousands separators in JavaScript
...h commas as thousands separators. For example, I want to show the number 1234567 as "1,234,567". How would I go about doing this?
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How to count the frequency of the elements in an unordered list?
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33 Answers
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Is there a difference between using a dict literal and a dict constructor?
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answered Jul 7 '11 at 12:43
John La RooyJohn La Rooy
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Python 3: UnboundLocalError: local variable referenced before assignment [duplicate]
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Jakob BowyerJakob Bowyer
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