大约有 40,000 项符合查询结果（耗时：0.0588秒） [XML]
Primary key or Unique index?
...ork we have a big database with unique indexes instead of primary keys and all works fine.
15 Answers
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Why use 'virtual' for class properties in Entity Framework model definitions?
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It allows the Entity Framework to create a proxy around the virtual property so that the property can support lazy loading and more efficient change tracking. See What effect(s) can the virtual keyword have in Entity Framework 4...
Combine two ActiveRecord::Relation objects
...lation.or(last_name_relation)
† Only in ActiveRecord 5+; for 4.2 install the where-or backport.
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Using javadoc for Python documentation [closed]
... from the Napolean documentation linked above.
A comprehensive example on all types of docstrings here.
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What is a lambda (function)?
...us and refers to anonymous functions in programming.
Why is this cool? It allows you to write quick throw away functions without naming them. It also provides a nice way to write closures. With that power you can do things like this.
Python
def adder(x):
return lambda y: x + y
add5 = adder(5)...
Amazon S3 boto - how to create a folder?
...y S3 access tools like S3Fox show like a directory structure, but it's actually just a single file in a bucket.
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Reducing the space between sections of the UITableView
... viewForHeaderInSection:(NSInteger)section {
return [[UIView alloc] initWithFrame:CGRectZero];
}
- (UIView*)tableView:(UITableView*)tableView
viewForFooterInSection:(NSInteger)section {
return [[UIView alloc] initWithFrame:CGRectZero];
}
Change the values accordingly...
Improve INSERT-per-second performance of SQLite
...more memory will be used for your database.
If you have indices, consider calling CREATE INDEX after doing all your inserts. This is significantly faster than creating the index and then doing your inserts.
You have to be quite careful if you have concurrent access to SQLite, as the whole database i...
What is Func, how and when is it used
...PrintListToConsole<T> {
private PrintListConsoleRender<T> _renderer;
public void SetRenderer(PrintListConsoleRender<T> r) {
// this is the point where I can personalize the render mechanism
_renderer = r;
}
public void PrintToConsole(List<T>...
Efficient way to determine number of digits in an integer
...For added efficiency, if you know that your input numbers will be mostly small ones (I'm guessing less than 100,000), then reverse the tests: if (x < 10) return 1; if (x < 100) return 2; etc., so that the function will do less tests and exit faster.
– squelart
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