大约有 42,000 项符合查询结果（耗时：0.0416秒） [XML]
What is the meaning and difference between subject, user and principal?
In the context of security frameworks, a few terms commonly occur subject , user and principal , of which I have not been able to find a clear definition and the difference between them.
...
When and why are database joins expensive?
I'm doing some research into databases and I'm looking at some limitations of relational DBs.
7 Answers
...
Conditional Variable vs Semaphore
When should one use a semaphore and when should one use a conditional variable (CondVar) ?
6 Answers
...
When to use Common Table Expression (CTE)
I have begun reading about Common Table Expression and cannot think of a use case where I would need to use them. They would seem to be redundant as the same can be done with derived tables. Is there something I am missing or not understanding well? Can someone give me a simple example of limitati...
Should I use pt or px?
What is the difference between pt and px in CSS? Which one should I use and why?
5 Answers
...
What is a “static” function in C?
The question was about plain c functions, not c++ static methods, as clarified in comments.
12 Answers
...
Getting attributes of a class
I want to get the attributes of a class, say:
18 Answers
18
...
What is the advantage of using abstract classes instead of traits?
What is the advantage of using an abstract class instead of a trait (apart from performance)? It seems like abstract classes can be replaced by traits in most cases.
...
PHP - How to check if a string contains a specific text [duplicate]
Suppose I have the code above, how to write the statement "if($a exist 'some text')"?
8 Answers
...
Does JSON syntax allow duplicate keys in an object?
Is this valid json?
12 Answers
12
...