大约有 47,000 项符合查询结果（耗时：0.0427秒） [XML]
Simulate CREATE DATABASE IF NOT EXISTS for PostgreSQL?
...an work around it from within psql by executing the DDL statement conditionally:
SELECT 'CREATE DATABASE mydb'
WHERE NOT EXISTS (SELECT FROM pg_database WHERE datname = 'mydb')\gexec
The manual:
\gexec
Sends the current query buffer to the server, then treats each column of each row of the query's...
setTimeout / clearTimeout problems
... Christian C. SalvadóChristian C. Salvadó
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Check if OneToOneField is None in Django
... Thank you for this solution. Unfortunately, this doesn't work all the time. In case you want to work with select_related() now or in the future -- or maybe even to be sure you also handle other sorts of magic which may happen elsewhere -- you have to extend the test as follows: if hasat...
How to find serial number of Android device?
...ected by the ANDROID_ID bug in 2.2.
As far as I've been able to determine, all affected devices have the same ANDROID_ID, which is 9774d56d682e549c. Which is also the same device id reported by the emulator, btw.
Google believes that OEMs have patched the issue for many or most of their devices, bu...
Copy folder recursively in node.js
Is there an easier way to copy a folder and all its content without manually doing a sequence of fs.readir , fs.readfile , fs.writefile recursively ?
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Why use Ruby's attr_accessor, attr_reader and attr_writer?
...write classes which will work correctly no matter how their public API is called.
class Person
attr_accessor :age
...
end
Here, I can see that I may both read and write the age.
class Person
attr_reader :age
...
end
Here, I can see that I may only read the age. Imagine that it is set ...
What is Prefix.pch file in Xcode?
...uestion has been already answered in thread I'm linking below. It contains all the information you need as well as useful comments.
Is it OK to remove Prefix.pch file from the Xcode project?
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Get selected subcommand with argparse
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answered Jan 1 '11 at 21:10
robertrobert
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Python Threading String Arguments
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answered Jul 11 '10 at 2:54
StephenStephen
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How do I run a Ruby file in a Rails environment?
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#!/usr/bin/env /Users/me/rails_project/script/rails runner
Product.all.each { |p| p.price *= 2 ; p.save! }
-------------------------------------------------------------
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