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difference between primary key and unique key
...d on multiple columns, e.g. Primary key (CustomerID, ProductID). This is called composite primary key. This is to clarify the first point, as it might be take as it is (read one key => one column ) by new comer to sql : )
– ken
Apr 10 '14 at 13:53
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How do I save a UIImage to a file?
...// Save image.
[UIImagePNGRepresentation(image) writeToFile:filePath atomically:YES];
Core Data has nothing to do with saving images to disk by the way.
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Plot two histograms on single chart with matplotlib
...dom
import numpy
from matplotlib import pyplot
x = [random.gauss(3,1) for _ in range(400)]
y = [random.gauss(4,2) for _ in range(400)]
bins = numpy.linspace(-10, 10, 100)
pyplot.hist(x, bins, alpha=0.5, label='x')
pyplot.hist(y, bins, alpha=0.5, label='y')
pyplot.legend(loc='upper right')
pyplot....
Can you animate a height change on a UITableViewCell when selected?
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I found a REALLY SIMPLE solution to this as a side-effect to a UITableView I was working on.....
Store the cell height in a variable that reports the original height normally via the tableView: heightForRowAtIndexPath:, then when you wa...
Efficient way to determine number of digits in an integer
...For added efficiency, if you know that your input numbers will be mostly small ones (I'm guessing less than 100,000), then reverse the tests: if (x < 10) return 1; if (x < 100) return 2; etc., so that the function will do less tests and exit faster.
– squelart
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How do you disable browser Autocomplete on web form field / input tag?
...t it both on the form, AND on the input element itself. That way you cover all the nonstandardness of browsers.
– AviD
Dec 13 '10 at 12:11
85
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Best way to do Version Control for MS Excel
...lution here.
The solution for me was to create a spreadsheet that exports all modules on save, and removes and re-imports the modules on open. Yes, this could be potentially dangerous for converting existing spreadsheets.
This allows me to edit the macros in the modules via Emacs (yes, emacs) or n...
How to reset sequence in postgres and fill id column with new data?
... This might cause duplicate ids. To prevent this, you can first set all to very high values: UPDATE t SET idcolumn=1000000+ nextval('seq'); then run the above script.
– tahagh
Nov 28 '13 at 13:15
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How to make a class conform to a protocol in Swift?
...aSource'
Is expected. You will get the error until your class implements all required methods of the protocol.
So get coding :)
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Remove rows with duplicate indices (Pandas DataFrame and TimeSeries)
...Pandas Index itself:
df3 = df3[~df3.index.duplicated(keep='first')]
While all the other methods work, the currently accepted answer is by far the least performant for the provided example. Furthermore, while the groupby method is only slightly less performant, I find the duplicated method to be mor...