大约有 47,000 项符合查询结果（耗时：0.0815秒） [XML]
Does MySQL ignore null values on unique constraints?
... '1' for key 'x'
INSERT table1 VALUES (NULL);
INSERT table1 VALUES (NULL);
SELECT * FROM table1;
Result:
x
NULL
NULL
1
This is not true for all databases. SQL Server 2005 and older, for example, only allows a single NULL value in a column that has a unique constraint.
...
HashSet versus Dictionary w.r.t searching time to find if an item exists
...value);
}
var testPoints = Enumerable.Repeat(1, TestReps).Select(_ => rand.Next()).ToArray();
var timer = new Stopwatch();
var total = 0;
timer.Restart();
for (int i = 0; i < TestReps; i++)
{
var newKey =...
Can I keep Nuget on the jQuery 1.9.x/1.x path (instead of upgrading to 2.x)?
...UI update is working for me (after allowedVersions added). UI doesnt allow selection of any projects when update is attempted
– RockResolve
Feb 3 '14 at 21:45
...
Paging in a Rest Collection
... would identify a concrete resource (be it a resource in a specific state, selection of resources, or discrete result), it goes in the URL. Search queries, pagination, and restful transactions are good examples of this. If its something that is needed to transform the abstract representation to a ...
How to have no pagebreak after \include in LaTeX
...e!
use \include instead of \input, and use the \includeonly command to select sections to process
share
|
improve this answer
|
follow
|
...
Entity Framework 4 - AddObject vs Attach
...m d in context.Destinations
where d.Name == "Grand Canyon"
select d).Single();
}
DeleteDestination(canyon);
}
private static void DeleteDestination(Destination destination)
{
using (var context = new BreakAwayContext())
{
context.Destinations.Attach(destinatio...
How can I see all the issues I'm watching on Github?
...m any page by clicking the notification/bell icon on the top left and then selecting "Managed Notification" > "Subscriptions" from the left menu panel.
share
|
improve this answer
|
...
App Inventor 2 CustomWebView 拓展：高级版Web浏览器，完美浏览现代Web前...
...ebView loads pages in overview mode
LongClickable
Returns whether text selection and context menu are enabled or not
OverScrollMode
Gets over scroll mode
PromptForPermission
Sets whether webview will prompt for permission and raise ‘OnPermissionRequest’ event or not else assume permi...
Will Try / Finally (without the Catch) bubble the exception?
...such a delegate would allow the code which manipulated the object state to select appropriate cleanup action if it's disrupted. Such actions might include repairing the data structure and returning True, throwing another "more severe" exception which wraps the original one, or letting the original ...
Are class names in CSS selectors case sensitive?
I keep reading everywhere that CSS is not case sensitive, but I have this selector
4 Answers
...