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How to concatenate columns in a Postgres SELECT?
...catenated to NULL is NULL. If NULL values can be involved and the result shall not be NULL, use concat_ws() to concatenate any number of values (Postgres 9.1 or later):
SELECT concat_ws(', ', a, b) AS ab FROM foo;
Or concat() if you don't need separators:
SELECT concat(a, b) AS ab FROM foo;
No...
throwing exceptions out of a destructor
...f an element destructor throws, the vector destruction fails... There is really no good way to protect against exceptions thrown from destructors, so the library makes no guarantees if an element destructor throws" (from Appendix E3.2) .
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Having options in argparse with a dash
...scores:
import argparse
pa = argparse.ArgumentParser()
pa.add_argument('--foo-bar')
args = pa.parse_args(['--foo-bar', '24'])
print args # Namespace(foo_bar='24')
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Simple explanation of clojure protocols
...eployed, separately type checked. We want them to be type-safe. [Note: not all of these make sense in all languages. But, for example, the goal to have them type-safe makes sense even in a language like Clojure. Just because we can't statically check type-safety doesn't mean that we want our code to...
Get next / previous element using JavaScript?
... page
var selectionDiv = document.getElementById("MySecondDiv");
So basically with selectionDiv iterate through the collection to find its index, and then obviously -1 = previous +1 = next within bounds
for(var i = 0; i < divs.length;i++)
{
if(divs[i] == selectionDiv)
{
var previous...
Executing periodic actions in Python [duplicate]
I am working on Windows. I want to execute a function foo() every 10 seconds.
9 Answers
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Why does calling a method in my derived class call the base class method?
...owInfo()
{
Console.WriteLine("I am a student!");
}
}
If called, the behavior of ShowInfo varies, based on the implementation:
Person person = new Teacher();
person.ShowInfo(); // Shows 'I am a teacher!'
person = new Student();
person.ShowInfo(); // Shows 'I am a student!'
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What is a “symbol” in Julia?
...its own variables. I.e., you need a way to represent – as data – the foo on the left hand side of this:
foo == "foo"
Now we're getting to the heart of the matter: the difference between a symbol and a string is the difference between foo on the left hand side of that comparison and "foo" on...
How do I assert an Iterable contains elements with a certain property?
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Its not especially Hamcrest, but I think it worth to mention here. What I use quite often in Java8 is something like:
assertTrue(myClass.getMyItems().stream().anyMatch(item -> "foo".equals(item.getName())));
(Edited to Rodrigo Manyar...
Increment value in mysql update query
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Also, to "increment" string, when update, use CONCAT
update dbo.test set foo=CONCAT(foo, 'bar') where 1=1
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