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What is the single most influential book every programmer should read? [closed]
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Code Complete (2nd edition) by Steve McConnell
The Pragmatic Programmer
Structure and Interpretation of Computer Programs
The C Programming Language by Kernighan and Ritchie
Introduction to Algorithms by Cormen, Leiserson, Rivest & Stein
Design Patt...
what is the difference between GROUP BY and ORDER BY in sql
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ORDER BY alters the order in which items are returned.
GROUP BY will aggregate records by the specified columns which allows you to perform aggregation functions on non-grouped columns (such as SUM, COUNT, AVG, etc).
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SQL Server: Difference between PARTITION BY and GROUP BY
I've been using GROUP BY for all types of aggregate queries over the years. Recently, I've been reverse-engineering some code that uses PARTITION BY to perform aggregations. In reading through all the documentation I can find about PARTITION BY , it sounds a lot like GROUP BY , maybe with a ...
Is it possible to GROUP BY multiple columns using MySQL?
Is it possible to GROUP BY more than one column in a MySQL SELECT query? For example:
7 Answers
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What's the difference between passing by reference vs. passing by value?
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First and foremost, the "pass by value vs. pass by reference" distinction as defined in the CS theory is now obsolete because the technique originally defined as "pass by reference" has since fallen out of favor and is seldom used now.1
Newer languages2 ...
Is Ruby pass by reference or by value?
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In traditional terminology, Ruby is strictly pass-by-value. But that's not really what you're asking here.
Ruby doesn't have any concept of a pure, non-reference value, so you certainly can't pass one to a method. Variables are always references to objec...
Is it better in C++ to pass by value or pass by constant reference?
Is it better in C++ to pass by value or pass by constant reference?
10 Answers
10
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Using group by on multiple columns
I understand the point of GROUP BY x .
2 Answers
2
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Are arrays passed by value or passed by reference in Java? [duplicate]
...itive type in Java, but they are not objects either , so are they passed by value or by reference? Does it depend on what the array contains, for example references or a primitive type?
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How to sort an array in descending order in Ruby
... on the various suggested answers. Here's what I found out:
#!/usr/bin/ruby
require 'benchmark'
ary = []
1000.times {
ary << {:bar => rand(1000)}
}
n = 500
Benchmark.bm(20) do |x|
x.report("sort") { n.times { ary.sort{ |a,b| b[:bar] <=> a[:bar] } } }
x.repor...