大约有 42,000 项符合查询结果（耗时：0.0523秒） [XML]
Difference between a theta join, equijoin and natural join
I'm having trouble understanding relational algebra when it comes to theta joins, equijoins and natural joins. Could someone please help me better understand it? If I use the = sign on a theta join is it exactly the same as just using a natural join?
...
Best documentation for Boost:asio?
...
First, I've been using Boost.Asio for quite a while already -- and I share your concern. To address your question:
There really is very scarce documentation about Boost.Asio aside from the introduction and tutorial. I am not the author, but this is mostly because there are just too man...
How do I move forward and backward between commits in git?
I am doing a git bisect and after arriving to the problematic commit, I am now trying to get a step forward/backward to make sure I am in the right one.
...
Can I set background image and opacity in the same property?
I can see in CSS references how to set image transparency and how to set a background image . But how can I combine these two in order to set a transparent background image?
...
input type=file show only button
...
This answer is so simple and elegant and has worked for all browsers.
– Mike.C.Ford
Mar 19 '15 at 15:55
...
Unit Testing AngularJS directive with templateUrl
... ngMock. The ngMock module is automatically loaded for every Angular test, and it initializes the mock $httpBackend to handle any use of the $http service, which includes template fetching. The template system tries to load the template through $http and it becomes an "unexpected request" to the moc...
When should I use the Visitor Design Pattern? [closed]
...dmit, I just don't get it. I read the wikipedia article for the pattern and I understand its mechanics but I'm still confused as to when I'd use it.
...
Why are unnamed namespaces used and what are their benefits?
I just joined a new C++ software project and I'm trying to understand the design. The project makes frequent use of unnamed namespaces. For example, something like this may occur in a class definition file:
...
What is the best Java email address validation method? [closed]
...verification email to the address if you want to ensure it's a real email, and that the owner wants it used on your site.
EDIT: There was a bug where it was too restrictive on domain, causing it to not accept valid emails from new TLDs.
This bug was resolved on 03/Jan/15 02:48 in commons-validator ...
How to convert a string into double and vice versa?
I want to convert a string into a double and after doing some math on it, convert it back to a string.
12 Answers
...