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How to check status of PostgreSQL server Mac OS X
...using psql to run a simple query and checking the exit code, e.g. psql -c 'SELECT 1', or use pg_isready to check the connection status.
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Getting “CHECKOUT can only be performed on a version resource” when trying to commit using Eclipse s
...om my project (by right clicking on the project from the package explorer, selecting "Team" -> "Commit"), I get the error:
...
XDocument or XmlDocument
...er>
XElement customersElement = new XElement("customers",
customers.Select(c => new XElement("customer",
new XAttribute("name", c.Name),
new XAttribute("lastSeen", c.LastOrder)
new XElement("address",
new XAttribute("town", c.Town),
new XAttr...
Using varchar(MAX) vs TEXT on SQL Server
...es ('b')
insert into @table values ('c')
insert into @table values ('d')
select *
from @table
where a ='a'
This give an error:
The data types text and varchar are incompatible in the equal to operator.
Wheras this does not:
declare @table table (a varchar(max))
Interestingly, LIKE still wo...
Look up all descendants of a class in Ruby
...e:
class Parent
def self.descendants
ObjectSpace.each_object(Class).select { |klass| klass < self }
end
end
class Child < Parent
end
class GrandChild < Child
end
puts Parent.descendants
puts Child.descendants
puts Parent.descendants gives you:
GrandChild
Child
puts Child.de...
Can you use hash navigation without affecting history?
...
Unless you use :target selectors ... then history functions are useless, as that part of the spec (css interaction with history ops) seems to be not defined currently, and style does not get recomputed on history replace by most/all browsers.
...
Is using Random and OrderBy a good shuffle algorithm?
...e naive version). Durstenfeld/Knuth achieve O(n) not by assignment, but by selection from a decreasing set and swapping. This way the random number selected may repeat and the algorithm only takes O(n).
– tvanfosson
Aug 17 '09 at 12:18
...
Using JQuery to check if no radio button in a group has been checked
... answer worked for me reliably to check whether a radio button group had a selected value. Best answer in the thread.
– Andy Cook
Apr 29 '13 at 19:21
1
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“Diff” an image using ImageMagick
...th layers, 3) remove alpha channels from both layers in the Layers tab, 4) select the G + B channels on one layer, select all and clear the channels with black color, the same with the R + B channels on the second layer, 4) set Screen mode for the upper layer in the Layers tab.
...
When should std::move be used on a function return value? [duplicate]
...e object to be copied is designated by an lvalue, overload
resolution to select the constructor for the copy is first performed as
if the object were designated by an rvalue.
return foo; is a case of NRVO, so copy elision is permitted. foo is an lvalue. So the constructor selected for the "co...