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How do I (or can I) SELECT DISTINCT on multiple columns?
I need to retrieve all rows from a table where 2 columns combined are all different. So I want all the sales that do not have any other sales that happened on the same day for the same price. The sales that are unique based on day and price will get updated to an active status.
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A quick and easy way to join array elements with a separator (the opposite of split) in Java [duplic
... directly specifying the elements
String joined1 = String.join(",", "a", "b", "c");
2) using arrays
String[] array = new String[] { "a", "b", "c" };
String joined2 = String.join(",", array);
3) using iterables
List<String> list = Arrays.asList(array);
String joined3 = String.join(",", l...
Can you issue pull requests from the command line on GitHub?
It seems like you have to interact with github.com to initiate a pull request. Is this so?
9 Answers
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Haskell offline documentation?
What are the possibilities, if any, for getting offline docs for Haskell core libraries (and maybe more)?
9 Answers
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What is the meaning of the term “free function” in C++?
While reading the documentation for boost::test, I came across the term "free function". What I understand is that a free function is any function that doesn't return anything (Its return type is void). But after reading further it seems that free functions also don't take any arguments. But I am no...
Compare two files line by line and generate the difference in another file
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diff(1) is not the answer, but comm(1) is.
NAME
comm - compare two sorted files line by line
SYNOPSIS
comm [OPTION]... FILE1 FILE2
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-1 suppress lines unique to FILE1
-2 suppress lines unique to FILE2
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Insert the carriage return character in vim
I'm editing a network protocol frame stored a file in Unix ( \n newlines). I need to insert the carriage return character ( U+000D aka \r ). When I try to paste it from the clipboard ( "+p ) or type it using Ctrl + Shift + u - 000d , the linefeed is inserted ( U+000A ).
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Is it possible to make abstract classes in Python?
How can I make a class or method abstract in Python?
12 Answers
12
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What do 3 dots next to a parameter type mean in Java?
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It means that zero or more String objects (or a single array of them) may be passed as the argument(s) for that method.
See the "Arbitrary Number of Arguments" section here: http://java.sun.com/docs/books/tutorial/java/javaOO/arguments.html#varargs
In your exa...
Most efficient way to prepend a value to an array
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I'm not sure about more efficient in terms of big-O but certainly using the unshift method is more concise:
var a = [1, 2, 3, 4];
a.unshift(0);
a; // => [0, 1, 2, 3, 4]
[Edit]
This jsPerf benchmark shows that unshift is decently fas...