大约有 860 项符合查询结果（耗时：0.0318秒） [XML]
INSERT IF NOT EXISTS ELSE UPDATE?
...NULL, 1, 2, 5);
The "SELECT * FROM data" will give you:
2|2|2|3.0
3|1|2|5.0
Note that the data.id is "3" and not "1" because REPLACE does a DELETE and INSERT, not an UPDATE. This also means that you must ensure that you define all necessary columns or you will get unexpected NULL values.
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Are Java static initializers thread safe?
...or lazy initialization
enum Singleton {
INSTANCE;
}
or for pre Java 5.0
class Singleton {
static class SingletonHolder {
static final Singleton INSTANCE = new Singleton();
}
public static Singleton instance() {
return SingletonHolder.INSTANCE;
}
}
As the static bloc...
UIImagePickerController error: Snapshotting a view that has not been rendered results in an empty sn
...e with Apple's PhotoPicker sample code project.
I was using Xcode Version 5.0 and iOS 7.0.3 on an iPhone 4.
Steps to Reproduce:
Download Apple's PhotoPicker sample project at
https://developer.apple.com/library/ios/samplecode/PhotoPicker/Introduction/Intro.html
In APLViewController.m comment ou...
How to deal with “java.lang.OutOfMemoryError: Java heap space” error?
...d objects in the memory. After a quick research I found Ergonomics in the 5.0 Java Virtual Machine and others saying on Windows machine the JVM defaults max heap size as 64MB .
...
Why does InetAddress.isReachable return false, when I can ping the IP address?
...onnected" for one IPv4 and one IPv6 address. The bug is also fixed in Java 5.0 b22. Maybe isReachable is more reliable now days.
– Lii
Jan 23 at 15:10
...
Can I change multiplier property for NSLayoutConstraint?
... YES;
[self.view layoutIfNeeded]; // or using [UIView animate ...]
Swift 5.0 version
var standardConstraint: NSLayoutConstraint!
var zoomedConstraint: NSLayoutConstraint!
// ...
// switch between constraints
standardConstraint.isActive = false // this line should always be the first line. becau...
What are the uses of “using” in C#?
...an create aliases for namespaces and types, as pointed out in the book "C# 5.0 In a Nutshell: The Definitive Guide" (http://www.amazon.com/5-0-Nutshell-The-Definitive-Reference-ebook/dp/B008E6I1K8), by Joseph and Ben Albahari. One example:
namespace HelloWorld
{
using AppFunc = Func<IDictio...
Rails 4: how to use $(document).ready() with turbo-links
...heck your Gemfile.lock for the turbolinks version used. If it is less then 5.0 then use page:change or upgrade turbolinks. Also found this, may be relevant to some, where turbolinks translates events to the old event names: github.com/turbolinks/turbolinks/blob/v5.0.0/src/turbolinks/…
...
Cross-thread operation not valid: Control accessed from a thread other than the thread it was create
...swers on question How to update the GUI from another thread in C#?.
For C# 5.0 and .NET 4.5 the recommended solution is here.
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How to recover MySQL database from .myd, .myi, .frm files
...y're only views into internal database state. See dev.mysql.com/doc/refman/5.0/en/information-schema.html
– brian-brazil
May 18 '09 at 19:41
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