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Can a foreign key be NULL and/or duplicate?
...0.
2 - Yes, as long as it's not a UNIQUE constraint or linked to a unique index.
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Best way to merge two maps and sum the values of same key?
...mutable.Map[Int,Int] = Map(1 -> 109, 3 -> 300, 2 -> 20)
Specifically, the binary operator for Map[K, V] combines the keys of the maps, folding V's semigroup operator over any duplicate values. The standard semigroup for Int uses the addition operator, so you get the sum of values for eac...
Putting git hooks into repository
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I generally agree with Scytale, with a couple additional suggestions, enough that it's worth a separate answer.
First, you should write a script which creates the appropriate symlinks, especially if these hooks are about enforcing ...
ASP.NET MVC: Custom Validation by DataAnnotation
...ationContext.ObjectInstance, null)).OfType<string>();
var totalLength = values.Sum(x => x.Length) + Convert.ToString(value).Length;
if (totalLength < this.MinLength)
{
return new ValidationResult(this.FormatErrorMessage(validationContext.DisplayName));...
Image Greyscale with CSS & re-color on mouse-over?
...rayscale(100%);
/* Chrome 19+ & Safari 6+ */
-webkit-transition: all .6s ease;
/* Fade to color for Chrome and Safari */
-webkit-backface-visibility: hidden;
/* Fix for transition flickering */
}
img.grayscale:hover {
filter: none;
-webkit-filter: grayscale(0%);
}
sv...
What are Flask Blueprints, exactly?
...he string mold in Blueprint("mold", __name__)
– Codevalley
Aug 7 '17 at 6:48
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How can I profile Python code line-by-line?
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can anyone show how to actually use this library? The readme teaches how to install, and answers various FAQs, but doesn't mention how to use it after a pip install..
– cryanbhu
Jul 25 '18 at 3:28
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Inject errors into already validated form?
...external) process for further processing. This external process can potentially find further errors in the values.
4 Answer...
Git: fatal: Pathspec is in submodule
I'm trying to get TravisCI to automatically deploy my Hakyll static site, according to this guide .
5 Answers
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How to delete duplicate lines in a file without sorting it in Unix?
... To save it in a file we can do this awk '!seen[$0]++' merge_all.txt > output.txt
– Akash Kandpal
Jul 19 '18 at 11:42
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