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Why use multiple columns as primary keys (composite primary key)
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Your understanding is correct.
You would do this in many cases. One example is in a relationship like OrderHeader and OrderDetail. The PK in OrderHeader might be OrderNumber. The PK in OrderDetail might be OrderNumber AND LineNumber. If it was either of those two, it would not be unique...
Case objects vs Enumerations in Scala
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One big difference is that Enumerations come with support for instantiating them from some name String. For example:
object Currency extends Enumeration {
val GBP = Value("GBP")
val EUR = Value("EUR") //etc.
}
Then yo...
Find nearest value in numpy array
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Actually, that still only works for one dimension, since argmin() gives multiple results per column / dimension. Also I had a typo. This works, at least for 2 dimensions: a[np.sum(np.square(np.abs(a-a0)),1).argmin()].
– Max Shron
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How to specify font attributes for all elements on an html web page?
... Agree, but it applies the CSS to ALL elements, as BugAlert asked for. If one wants to effect ALL elements, one can expect the performance to reduce a little. :)
– Bazzz
Oct 22 '10 at 14:05
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How to parse a query string into a NameValueCollection in .NET
...hy to install 100 M of additional libraries on client computer to just use one simple method? However, it looks like Microsoft doesn't have any better idea. The only way is to implement own method or use open source implementation.
– Vitalii
Jun 1 '12 at 12:05
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Post parameter is always null
... I'm having some real odd issue when calling POST on my WebAPI.
I've even gone back to the basic version generated on new project. So:
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Where is git.exe located?
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why was this so difficult
– Jonesopolis
Aug 26 '14 at 16:19
18
Its locate...
Cluster analysis in R: determine the optimal number of clusters
...y = unlist(lapply(1:g, function(i) rnorm(n/g, runif(1)*i^2))))
plot(d)
One. Look for a bend or elbow in the sum of squared error (SSE) scree plot. See http://www.statmethods.net/advstats/cluster.html & http://www.mattpeeples.net/kmeans.html for more. The location of the elbow in the resultin...
What is the best way to convert an array to a hash in Ruby
In Ruby, given an array in one of the following forms...
11 Answers
11
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How to use gitignore command in git
...it rm --cached doc/*
If you don't already have a .gitignore, you can make one right inside of your project folder: project/.gitignore.
Put doc/* in the .gitignore
Stage the file to commit: git add project/.gitignore
Commit: git commit -m "message".
Push your change to github.
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